diff --git a/accessible/src/windows/ia2/ia2AccessibleAction.cpp b/accessible/src/windows/ia2/ia2AccessibleAction.cpp
index 2bbc422b79a3..f0968e884c94 100644
--- a/accessible/src/windows/ia2/ia2AccessibleAction.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleAction.cpp
@@ -19,6 +19,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleAction::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleAction == iid) {
@@ -73,6 +76,9 @@ ia2AccessibleAction::get_description(long aActionIndex, BSTR *aDescription)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aDescription)
+    return E_INVALIDARG;
+
   *aDescription = nullptr;
 
   AccessibleWrap* acc = static_cast<AccessibleWrap*>(this);
@@ -150,6 +156,9 @@ ia2AccessibleAction::get_name(long aActionIndex, BSTR *aName)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aName)
+    return E_INVALIDARG;
+
   *aName = nullptr;
 
   AccessibleWrap* acc = static_cast<AccessibleWrap*>(this);
@@ -176,6 +185,9 @@ ia2AccessibleAction::get_localizedName(long aActionIndex, BSTR *aLocalizedName)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aLocalizedName)
+    return E_INVALIDARG;
+
   *aLocalizedName = nullptr;
   return E_NOTIMPL;
 
diff --git a/accessible/src/windows/ia2/ia2AccessibleComponent.cpp b/accessible/src/windows/ia2/ia2AccessibleComponent.cpp
index 352ed0331374..3a62ed6bd15d 100644
--- a/accessible/src/windows/ia2/ia2AccessibleComponent.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleComponent.cpp
@@ -22,6 +22,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleComponent::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleComponent == iid) {
@@ -40,6 +43,9 @@ ia2AccessibleComponent::get_locationInParent(long* aX, long* aY)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aX || !aY)
+    return E_INVALIDARG;
+
   *aX = 0;
   *aY = 0;
 
@@ -87,6 +93,11 @@ ia2AccessibleComponent::get_foreground(IA2Color* aForeground)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aForeground)
+    return E_INVALIDARG;
+
+  *aForeground = 0;
+
   AccessibleWrap* acc = static_cast<AccessibleWrap*>(this);
   if (acc->IsDefunct())
     return CO_E_OBJNOTCONNECTED;
@@ -105,6 +116,11 @@ ia2AccessibleComponent::get_background(IA2Color* aBackground)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aBackground)
+    return E_INVALIDARG;
+
+  *aBackground = 0;
+
   AccessibleWrap* acc = static_cast<AccessibleWrap*>(this);
   if (acc->IsDefunct())
     return CO_E_OBJNOTCONNECTED;
diff --git a/accessible/src/windows/ia2/ia2AccessibleHyperlink.cpp b/accessible/src/windows/ia2/ia2AccessibleHyperlink.cpp
index 74048d2f90f3..173857261c22 100644
--- a/accessible/src/windows/ia2/ia2AccessibleHyperlink.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleHyperlink.cpp
@@ -19,6 +19,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleHyperlink::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleHyperlink == iid) {
@@ -40,6 +43,9 @@ ia2AccessibleHyperlink::get_anchor(long aIndex, VARIANT* aAnchor)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAnchor)
+    return E_INVALIDARG;
+
   VariantInit(aAnchor);
 
   Accessible* thisObj = static_cast<AccessibleWrap*>(this);
@@ -75,6 +81,9 @@ ia2AccessibleHyperlink::get_anchorTarget(long aIndex, VARIANT* aAnchorTarget)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAnchorTarget)
+    return E_INVALIDARG;
+
   VariantInit(aAnchorTarget);
 
   Accessible* thisObj = static_cast<AccessibleWrap*>(this);
@@ -118,6 +127,9 @@ ia2AccessibleHyperlink::get_startIndex(long* aIndex)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIndex)
+    return E_INVALIDARG;
+
   *aIndex = 0;
 
   Accessible* thisObj = static_cast<AccessibleWrap*>(this);
@@ -138,6 +150,9 @@ ia2AccessibleHyperlink::get_endIndex(long* aIndex)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIndex)
+    return E_INVALIDARG;
+
   *aIndex = 0;
 
   Accessible* thisObj = static_cast<AccessibleWrap*>(this);
@@ -158,6 +173,9 @@ ia2AccessibleHyperlink::get_valid(boolean* aValid)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aValid)
+    return E_INVALIDARG;
+
   *aValid = false;
 
   Accessible* thisObj = static_cast<AccessibleWrap*>(this);
diff --git a/accessible/src/windows/ia2/ia2AccessibleHypertext.cpp b/accessible/src/windows/ia2/ia2AccessibleHypertext.cpp
index 967ee7bab108..12af891db32a 100644
--- a/accessible/src/windows/ia2/ia2AccessibleHypertext.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleHypertext.cpp
@@ -21,6 +21,9 @@ ia2AccessibleHypertext::get_nHyperlinks(long* aHyperlinkCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aHyperlinkCount)
+    return E_INVALIDARG;
+
   *aHyperlinkCount = 0;
 
   HyperTextAccessibleWrap* hyperText = static_cast<HyperTextAccessibleWrap*>(this);
@@ -39,6 +42,9 @@ ia2AccessibleHypertext::get_hyperlink(long aLinkIndex,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aHyperlink)
+    return E_INVALIDARG;
+
   *aHyperlink = nullptr;
 
   HyperTextAccessibleWrap* hyperText = static_cast<HyperTextAccessibleWrap*>(this);
@@ -62,6 +68,9 @@ ia2AccessibleHypertext::get_hyperlinkIndex(long aCharIndex, long* aHyperlinkInde
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aHyperlinkIndex)
+    return E_INVALIDARG;
+
   *aHyperlinkIndex = 0;
 
   HyperTextAccessibleWrap* hyperAcc = static_cast<HyperTextAccessibleWrap*>(this);
diff --git a/accessible/src/windows/ia2/ia2AccessibleImage.cpp b/accessible/src/windows/ia2/ia2AccessibleImage.cpp
index 32c1376a02e4..116bcbb90836 100644
--- a/accessible/src/windows/ia2/ia2AccessibleImage.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleImage.cpp
@@ -23,6 +23,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleImage::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleImage == iid) {
@@ -41,6 +44,9 @@ ia2AccessibleImage::get_description(BSTR* aDescription)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aDescription)
+    return E_INVALIDARG;
+
   *aDescription = nullptr;
 
   ImageAccessibleWrap* acc = static_cast<ImageAccessibleWrap*>(this);
@@ -68,6 +74,9 @@ ia2AccessibleImage::get_imagePosition(enum IA2CoordinateType aCoordType,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aX || !aY)
+    return E_INVALIDARG;
+
   *aX = 0;
   *aY = 0;
 
@@ -96,6 +105,9 @@ ia2AccessibleImage::get_imageSize(long* aHeight, long* aWidth)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aHeight || !aWidth)
+    return E_INVALIDARG;
+
   *aHeight = 0;
   *aWidth = 0;
 
diff --git a/accessible/src/windows/ia2/ia2AccessibleTable.cpp b/accessible/src/windows/ia2/ia2AccessibleTable.cpp
index fffa119e040f..1139fe70efa8 100644
--- a/accessible/src/windows/ia2/ia2AccessibleTable.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleTable.cpp
@@ -26,6 +26,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleTable::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleTable == iid) {
@@ -59,6 +62,9 @@ ia2AccessibleTable::get_caption(IUnknown** aAccessible)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAccessible)
+    return E_INVALIDARG;
+
   *aAccessible = nullptr;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -79,6 +85,9 @@ ia2AccessibleTable::get_childIndex(long aRowIdx, long aColIdx,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aChildIdx)
+    return E_INVALIDARG;
+
   *aChildIdx = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -99,6 +108,9 @@ ia2AccessibleTable::get_columnDescription(long aColIdx, BSTR* aDescription)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aDescription)
+    return E_INVALIDARG;
+
   *aDescription = nullptr;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -123,6 +135,9 @@ ia2AccessibleTable::get_columnExtentAt(long aRowIdx, long aColIdx,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aSpan)
+    return E_INVALIDARG;
+
   *aSpan = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -144,6 +159,9 @@ ia2AccessibleTable::get_columnHeader(IAccessibleTable** aAccessibleTable,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAccessibleTable || !aStartingRowIndex)
+    return E_INVALIDARG;
+
   *aAccessibleTable = nullptr;
   *aStartingRowIndex = -1;
   return E_NOTIMPL;
@@ -156,6 +174,9 @@ ia2AccessibleTable::get_columnIndex(long aCellIdx, long* aColIdx)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aColIdx)
+    return E_INVALIDARG;
+
   *aColIdx = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -175,6 +196,9 @@ ia2AccessibleTable::get_nColumns(long* aColCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aColCount)
+    return E_INVALIDARG;
+
   *aColCount = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -190,6 +214,9 @@ ia2AccessibleTable::get_nRows(long* aRowCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowCount)
+    return E_INVALIDARG;
+
   *aRowCount = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -211,6 +238,9 @@ ia2AccessibleTable::get_nSelectedColumns(long* aColCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aColCount)
+    return E_INVALIDARG;
+
   *aColCount = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -226,6 +256,9 @@ ia2AccessibleTable::get_nSelectedRows(long* aRowCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowCount)
+    return E_INVALIDARG;
+
   *aRowCount = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -242,6 +275,9 @@ ia2AccessibleTable::get_rowDescription(long aRowIdx, BSTR* aDescription)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aDescription)
+    return E_INVALIDARG;
+
   *aDescription = nullptr;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -265,6 +301,9 @@ ia2AccessibleTable::get_rowExtentAt(long aRowIdx, long aColIdx, long* aSpan)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aSpan)
+    return E_INVALIDARG;
+
   *aSpan = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -286,6 +325,9 @@ ia2AccessibleTable::get_rowHeader(IAccessibleTable** aAccessibleTable,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAccessibleTable || !aStartingColumnIndex)
+    return E_INVALIDARG;
+
   *aAccessibleTable = nullptr;
   *aStartingColumnIndex = -1;
   return E_NOTIMPL;
@@ -298,6 +340,9 @@ ia2AccessibleTable::get_rowIndex(long aCellIdx, long* aRowIdx)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowIdx)
+    return E_INVALIDARG;
+
   *aRowIdx = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -318,6 +363,9 @@ ia2AccessibleTable::get_selectedChildren(long aMaxChildren, long** aChildren,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aChildren || !aNChildren)
+    return E_INVALIDARG;
+
   *aChildren = nullptr;
   *aNChildren = 0;
   if (!mTable)
@@ -366,6 +414,9 @@ ia2AccessibleTable::get_summary(IUnknown** aAccessible)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAccessible)
+    return E_INVALIDARG;
+
   // Neither html:table nor xul:tree nor ARIA grid/tree have an ability to
   // link an accessible object to specify a summary. There is closes method
   // in nsIAccessibleTable::summary to get a summary as a string which is not
@@ -382,6 +433,9 @@ ia2AccessibleTable::get_isColumnSelected(long aColIdx, boolean* aIsSelected)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIsSelected)
+    return E_INVALIDARG;
+
   *aIsSelected = false;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -400,6 +454,9 @@ ia2AccessibleTable::get_isRowSelected(long aRowIdx, boolean* aIsSelected)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIsSelected)
+    return E_INVALIDARG;
+
   *aIsSelected = false;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -419,6 +476,9 @@ ia2AccessibleTable::get_isSelected(long aRowIdx, long aColIdx,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIsSelected)
+    return E_INVALIDARG;
+
   *aIsSelected = false;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -511,6 +571,9 @@ ia2AccessibleTable::get_rowColumnExtentsAtIndex(long aCellIdx, long* aRowIdx,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowIdx || !aColIdx || !aRowExtents || !aColExtents || !aIsSelected)
+    return E_INVALIDARG;
+
   *aRowIdx = 0;
   *aColIdx = 0;
   *aRowExtents = 0;
@@ -550,6 +613,9 @@ ia2AccessibleTable::get_cellAt(long aRowIdx, long aColIdx, IUnknown** aCell)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCell)
+    return E_INVALIDARG;
+
   *aCell = nullptr;
 
   if (!mTable)
@@ -571,6 +637,9 @@ ia2AccessibleTable::get_nSelectedCells(long* aCellCount)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCellCount)
+    return E_INVALIDARG;
+
   *aCellCount = 0;
   if (!mTable)
     return CO_E_OBJNOTCONNECTED;
@@ -586,6 +655,9 @@ ia2AccessibleTable::get_selectedCells(IUnknown*** aCells, long* aNSelectedCells)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCells || !aNSelectedCells)
+    return E_INVALIDARG;
+
   *aCells = nullptr;
   *aNSelectedCells = 0;
   if (!mTable)
@@ -619,6 +691,9 @@ ia2AccessibleTable::get_selectedColumns(long** aColumns, long* aNColumns)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aColumns || !aNColumns)
+    return E_INVALIDARG;
+
   *aColumns = nullptr;
   *aNColumns = 0;
   if (!mTable)
@@ -646,6 +721,9 @@ ia2AccessibleTable::get_selectedRows(long** aRows, long* aNRows)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRows || !aNRows)
+    return E_INVALIDARG;
+
   *aRows = nullptr;
   *aNRows = 0;
   if (!mTable)
diff --git a/accessible/src/windows/ia2/ia2AccessibleTableCell.cpp b/accessible/src/windows/ia2/ia2AccessibleTableCell.cpp
index b0dc00feb12b..20f0f1ecd7bc 100644
--- a/accessible/src/windows/ia2/ia2AccessibleTableCell.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleTableCell.cpp
@@ -26,6 +26,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleTableCell::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleTableCell == iid) {
@@ -45,6 +48,9 @@ ia2AccessibleTableCell::get_table(IUnknown** aTable)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aTable)
+    return E_INVALIDARG;
+
   *aTable = nullptr;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
@@ -66,6 +72,9 @@ ia2AccessibleTableCell::get_columnExtent(long* aSpan)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aSpan)
+    return E_INVALIDARG;
+
   *aSpan = 0;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
@@ -83,6 +92,9 @@ ia2AccessibleTableCell::get_columnHeaderCells(IUnknown*** aCellAccessibles,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCellAccessibles || !aNColumnHeaderCells)
+    return E_INVALIDARG;
+
   *aCellAccessibles = nullptr;
   *aNColumnHeaderCells = 0;
   if (!mTableCell)
@@ -115,6 +127,9 @@ ia2AccessibleTableCell::get_columnIndex(long* aColIdx)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aColIdx)
+    return E_INVALIDARG;
+
   *aColIdx = -1;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
@@ -130,6 +145,9 @@ ia2AccessibleTableCell::get_rowExtent(long* aSpan)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aSpan)
+    return E_INVALIDARG;
+
   *aSpan = 0;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
@@ -146,6 +164,9 @@ ia2AccessibleTableCell::get_rowHeaderCells(IUnknown*** aCellAccessibles,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCellAccessibles || !aNRowHeaderCells)
+    return E_INVALIDARG;
+
   *aCellAccessibles = nullptr;
   *aNRowHeaderCells = 0;
   if (!mTableCell)
@@ -177,6 +198,9 @@ ia2AccessibleTableCell::get_rowIndex(long* aRowIdx)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowIdx)
+    return E_INVALIDARG;
+
   *aRowIdx = -1;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
@@ -195,6 +219,9 @@ ia2AccessibleTableCell::get_rowColumnExtents(long* aRowIdx, long* aColIdx,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRowIdx || !aColIdx || !aRowExtents || !aColExtents || !aIsSelected)
+    return E_INVALIDARG;
+
   *aRowIdx = *aColIdx = *aRowExtents = *aColExtents = 0;
   *aIsSelected = false;
   if (!mTableCell)
@@ -216,6 +243,9 @@ ia2AccessibleTableCell::get_isSelected(boolean* aIsSelected)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aIsSelected)
+    return E_INVALIDARG;
+
   *aIsSelected = false;
   if (!mTableCell)
     return CO_E_OBJNOTCONNECTED;
diff --git a/accessible/src/windows/ia2/ia2AccessibleText.cpp b/accessible/src/windows/ia2/ia2AccessibleText.cpp
index 22ed756bdcd2..3b9d9663dc13 100644
--- a/accessible/src/windows/ia2/ia2AccessibleText.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleText.cpp
@@ -76,6 +76,9 @@ ia2AccessibleText::get_caretOffset(long *aOffset)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aOffset)
+    return E_INVALIDARG;
+
   *aOffset = -1;
 
   HyperTextAccessible* textAcc = static_cast<HyperTextAccessibleWrap*>(this);
@@ -101,6 +104,9 @@ ia2AccessibleText::get_characterExtents(long aOffset,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aX || !aY || !aWidth || !aHeight)
+    return E_INVALIDARG;
+
   *aX = 0;
   *aY = 0;
   *aWidth = 0;
@@ -134,6 +140,9 @@ ia2AccessibleText::get_nSelections(long *aNSelections)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aNSelections)
+    return E_INVALIDARG;
+
   *aNSelections = 0;
 
   HyperTextAccessible* textAcc = static_cast<HyperTextAccessibleWrap*>(this);
@@ -158,6 +167,9 @@ ia2AccessibleText::get_offsetAtPoint(long aX, long aY,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aOffset)
+    return E_INVALIDARG;
+
   *aOffset = 0;
 
   HyperTextAccessible* textAcc = static_cast<HyperTextAccessibleWrap*>(this);
@@ -185,6 +197,9 @@ ia2AccessibleText::get_selection(long aSelectionIndex, long *aStartOffset,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aStartOffset || !aEndOffset)
+    return E_INVALIDARG;
+
   *aStartOffset = 0;
   *aEndOffset = 0;
 
@@ -210,6 +225,9 @@ ia2AccessibleText::get_text(long aStartOffset, long aEndOffset, BSTR *aText)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aText)
+    return E_INVALIDARG;
+
   *aText = nullptr;
 
   HyperTextAccessible* textAcc = static_cast<HyperTextAccessibleWrap*>(this);
@@ -238,6 +256,9 @@ ia2AccessibleText::get_textBeforeOffset(long aOffset,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aStartOffset || !aEndOffset || !aText)
+    return E_INVALIDARG;
+
   *aStartOffset = 0;
   *aEndOffset = 0;
   *aText = nullptr;
@@ -285,6 +306,9 @@ ia2AccessibleText::get_textAfterOffset(long aOffset,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aStartOffset || !aEndOffset || !aText)
+    return E_INVALIDARG;
+
   *aStartOffset = 0;
   *aEndOffset = 0;
   *aText = nullptr;
@@ -332,6 +356,9 @@ ia2AccessibleText::get_textAtOffset(long aOffset,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aStartOffset || !aEndOffset || !aText)
+    return E_INVALIDARG;
+
   *aStartOffset = 0;
   *aEndOffset = 0;
   *aText = nullptr;
@@ -423,6 +450,9 @@ ia2AccessibleText::get_nCharacters(long *aNCharacters)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aNCharacters)
+    return E_INVALIDARG;
+
   *aNCharacters = 0;
 
   HyperTextAccessible* textAcc = static_cast<HyperTextAccessibleWrap*>(this);
@@ -499,6 +529,9 @@ HRESULT
 ia2AccessibleText::GetModifiedText(bool aGetInsertedText,
                                    IA2TextSegment *aText)
 {
+  if (!aText)
+    return E_INVALIDARG;
+
   uint32_t startOffset = 0, endOffset = 0;
   nsAutoString text;
 
diff --git a/accessible/src/windows/ia2/ia2AccessibleValue.cpp b/accessible/src/windows/ia2/ia2AccessibleValue.cpp
index d9c13b53317d..7634ad9aa0a0 100644
--- a/accessible/src/windows/ia2/ia2AccessibleValue.cpp
+++ b/accessible/src/windows/ia2/ia2AccessibleValue.cpp
@@ -20,6 +20,9 @@ using namespace mozilla::a11y;
 STDMETHODIMP
 ia2AccessibleValue::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleValue == iid) {
@@ -43,6 +46,9 @@ ia2AccessibleValue::get_currentValue(VARIANT* aCurrentValue)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCurrentValue)
+    return E_INVALIDARG;
+
   VariantInit(aCurrentValue);
 
   AccessibleWrap* valueAcc = static_cast<AccessibleWrap*>(this);
@@ -84,6 +90,9 @@ ia2AccessibleValue::get_maximumValue(VARIANT* aMaximumValue)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aMaximumValue)
+    return E_INVALIDARG;
+
   VariantInit(aMaximumValue);
 
   AccessibleWrap* valueAcc = static_cast<AccessibleWrap*>(this);
@@ -107,6 +116,9 @@ ia2AccessibleValue::get_minimumValue(VARIANT* aMinimumValue)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aMinimumValue)
+    return E_INVALIDARG;
+
   VariantInit(aMinimumValue);
 
   AccessibleWrap* valueAcc = static_cast<AccessibleWrap*>(this);
diff --git a/accessible/src/windows/msaa/AccessibleWrap.cpp b/accessible/src/windows/msaa/AccessibleWrap.cpp
index a7c45ab5125e..e220b0305546 100644
--- a/accessible/src/windows/msaa/AccessibleWrap.cpp
+++ b/accessible/src/windows/msaa/AccessibleWrap.cpp
@@ -78,6 +78,9 @@ AccessibleWrap::QueryInterface(REFIID iid, void** ppv)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IUnknown == iid || IID_IDispatch == iid || IID_IAccessible == iid)
@@ -135,6 +138,9 @@ AccessibleWrap::get_accParent( IDispatch __RPC_FAR *__RPC_FAR *ppdispParent)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!ppdispParent)
+    return E_INVALIDARG;
+
   *ppdispParent = nullptr;
 
   if (IsDefunct())
@@ -195,6 +201,9 @@ AccessibleWrap::get_accChild(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!ppdispChild)
+    return E_INVALIDARG;
+
   *ppdispChild = nullptr;
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
@@ -224,6 +233,9 @@ AccessibleWrap::get_accName(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszName)
+    return E_INVALIDARG;
+
   *pszName = nullptr;
 
   if (IsDefunct())
@@ -261,6 +273,9 @@ AccessibleWrap::get_accValue(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszValue)
+    return E_INVALIDARG;
+
   *pszValue = nullptr;
 
   if (IsDefunct())
@@ -299,6 +314,9 @@ AccessibleWrap::get_accDescription(VARIANT varChild,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszDescription)
+    return E_INVALIDARG;
+
   *pszDescription = nullptr;
 
   if (IsDefunct())
@@ -328,6 +346,9 @@ AccessibleWrap::get_accRole(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pvarRole)
+    return E_INVALIDARG;
+
   VariantInit(pvarRole);
 
   if (IsDefunct())
@@ -423,6 +444,9 @@ AccessibleWrap::get_accState(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pvarState)
+    return E_INVALIDARG;
+
   VariantInit(pvarState);
   pvarState->vt = VT_I4;
   pvarState->lVal = 0;
@@ -461,6 +485,9 @@ AccessibleWrap::get_accHelp(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszHelp)
+    return E_INVALIDARG;
+
   *pszHelp = nullptr;
   return S_FALSE;
 
@@ -475,6 +502,9 @@ AccessibleWrap::get_accHelpTopic(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszHelpFile || !pidTopic)
+    return E_INVALIDARG;
+
   *pszHelpFile = nullptr;
   *pidTopic = 0;
   return S_FALSE;
@@ -523,6 +553,11 @@ AccessibleWrap::get_accFocus(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pvarChild)
+    return E_INVALIDARG;
+
+  VariantInit(pvarChild);
+
   // VT_EMPTY:    None. This object does not have the keyboard focus itself
   //              and does not contain a child that has the keyboard focus.
   // VT_I4:       lVal is CHILDID_SELF. The object itself has the keyboard focus.
@@ -532,8 +567,6 @@ AccessibleWrap::get_accFocus(
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
-  VariantInit(pvarChild);
-
   // Return the current IAccessible child that has focus
   Accessible* focusedAccessible = FocusedChild();
   if (focusedAccessible == this) {
@@ -692,6 +725,9 @@ AccessibleWrap::get_accSelection(VARIANT __RPC_FAR *pvarChildren)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pvarChildren)
+    return E_INVALIDARG;
+
   VariantInit(pvarChildren);
   pvarChildren->vt = VT_EMPTY;
 
@@ -724,6 +760,9 @@ AccessibleWrap::get_accDefaultAction(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pszDefaultAction)
+    return E_INVALIDARG;
+
   *pszDefaultAction = nullptr;
 
   if (IsDefunct())
@@ -800,6 +839,14 @@ AccessibleWrap::accLocation(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pxLeft || !pyTop || !pcxWidth || !pcyHeight)
+    return E_INVALIDARG;
+
+  *pxLeft = 0;
+  *pyTop = 0;
+  *pcxWidth = 0;
+  *pcyHeight = 0;
+
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
@@ -834,6 +881,8 @@ AccessibleWrap::accNavigate(
   if (!pvarEndUpAt)
     return E_INVALIDARG;
 
+  VariantInit(pvarEndUpAt);
+
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
@@ -844,8 +893,6 @@ AccessibleWrap::accNavigate(
   if (accessible->IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
-  VariantInit(pvarEndUpAt);
-
   Accessible* navAccessible = nullptr;
   int32_t xpRelation = -1;
 
@@ -952,6 +999,9 @@ AccessibleWrap::accHitTest(
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!pvarChild)
+    return E_INVALIDARG;
+
   VariantInit(pvarChild);
 
   if (IsDefunct())
@@ -1113,6 +1163,9 @@ AccessibleWrap::role(long *aRole)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aRole)
+    return E_INVALIDARG;
+
   *aRole = 0;
 
   if (IsDefunct())
@@ -1186,6 +1239,13 @@ AccessibleWrap::get_groupPosition(long *aGroupLevel,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aGroupLevel || !aSimilarItemsInGroup || !aPositionInGroup)
+    return E_INVALIDARG;
+
+  *aGroupLevel = 0;
+  *aSimilarItemsInGroup = 0;
+  *aPositionInGroup = 0;
+
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
@@ -1211,6 +1271,9 @@ AccessibleWrap::get_states(AccessibleStates *aStates)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aStates)
+    return E_INVALIDARG;
+
   *aStates = 0;
 
   // XXX: bug 344674 should come with better approach that we have here.
@@ -1269,6 +1332,9 @@ AccessibleWrap::get_extendedRole(BSTR *aExtendedRole)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aExtendedRole)
+    return E_INVALIDARG;
+
   *aExtendedRole = nullptr;
   return E_NOTIMPL;
 
@@ -1280,6 +1346,9 @@ AccessibleWrap::get_localizedExtendedRole(BSTR *aLocalizedExtendedRole)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aLocalizedExtendedRole)
+    return E_INVALIDARG;
+
   *aLocalizedExtendedRole = nullptr;
   return E_NOTIMPL;
 
@@ -1291,6 +1360,9 @@ AccessibleWrap::get_nExtendedStates(long *aNExtendedStates)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aNExtendedStates)
+    return E_INVALIDARG;
+
   *aNExtendedStates = 0;
   return E_NOTIMPL;
 
@@ -1304,6 +1376,9 @@ AccessibleWrap::get_extendedStates(long aMaxExtendedStates,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aExtendedStates || !aNExtendedStates)
+    return E_INVALIDARG;
+
   *aExtendedStates = nullptr;
   *aNExtendedStates = 0;
   return E_NOTIMPL;
@@ -1318,6 +1393,9 @@ AccessibleWrap::get_localizedExtendedStates(long aMaxLocalizedExtendedStates,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aLocalizedExtendedStates || !aNLocalizedExtendedStates)
+    return E_INVALIDARG;
+
   *aLocalizedExtendedStates = nullptr;
   *aNLocalizedExtendedStates = 0;
   return E_NOTIMPL;
@@ -1330,6 +1408,9 @@ AccessibleWrap::get_uniqueID(long *uniqueID)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!uniqueID)
+    return E_INVALIDARG;
+
   *uniqueID = - reinterpret_cast<intptr_t>(UniqueID());
   return S_OK;
 
@@ -1341,6 +1422,9 @@ AccessibleWrap::get_windowHandle(HWND *aWindowHandle)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aWindowHandle)
+    return E_INVALIDARG;
+
   *aWindowHandle = 0;
 
   if (IsDefunct())
@@ -1378,6 +1462,9 @@ AccessibleWrap::get_locale(IA2Locale *aLocale)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aLocale)
+    return E_INVALIDARG;
+
   // Language codes consist of a primary code and a possibly empty series of
   // subcodes: language-code = primary-code ( "-" subcode )*
   // Two-letter primary codes are reserved for [ISO639] language abbreviations.
@@ -1425,6 +1512,9 @@ AccessibleWrap::get_attributes(BSTR *aAttributes)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aAttributes)
+    return E_INVALIDARG;
+
   // The format is name:value;name:value; with \ for escaping these
   // characters ":;=,\".
   *aAttributes = nullptr;
@@ -1444,6 +1534,9 @@ AccessibleWrap::get_attributes(BSTR *aAttributes)
 STDMETHODIMP
 AccessibleWrap::GetTypeInfoCount(UINT *pctinfo)
 {
+  if (!pctinfo)
+    return E_INVALIDARG;
+
   *pctinfo = 1;
   return S_OK;
 }
@@ -1451,6 +1544,9 @@ AccessibleWrap::GetTypeInfoCount(UINT *pctinfo)
 STDMETHODIMP
 AccessibleWrap::GetTypeInfo(UINT iTInfo, LCID lcid, ITypeInfo **ppTInfo)
 {
+  if (!ppTInfo)
+    return E_INVALIDARG;
+
   *ppTInfo = nullptr;
 
   if (iTInfo != 0)
diff --git a/accessible/src/windows/msaa/ApplicationAccessibleWrap.cpp b/accessible/src/windows/msaa/ApplicationAccessibleWrap.cpp
index b2c57f509dc9..89690af337b3 100644
--- a/accessible/src/windows/msaa/ApplicationAccessibleWrap.cpp
+++ b/accessible/src/windows/msaa/ApplicationAccessibleWrap.cpp
@@ -48,6 +48,9 @@ ApplicationAccessibleWrap::NativeAttributes()
 STDMETHODIMP
 ApplicationAccessibleWrap::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_IAccessibleApplication == iid) {
@@ -67,6 +70,9 @@ ApplicationAccessibleWrap::get_appName(BSTR* aName)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aName)
+    return E_INVALIDARG;
+
   *aName = nullptr;
 
   if (IsDefunct())
@@ -91,6 +97,9 @@ ApplicationAccessibleWrap::get_appVersion(BSTR* aVersion)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aVersion)
+    return E_INVALIDARG;
+
   *aVersion = nullptr;
 
   if (IsDefunct())
@@ -115,6 +124,9 @@ ApplicationAccessibleWrap::get_toolkitName(BSTR* aName)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aName)
+    return E_INVALIDARG;
+
   if (IsDefunct())
     return CO_E_OBJNOTCONNECTED;
 
@@ -137,6 +149,9 @@ ApplicationAccessibleWrap::get_toolkitVersion(BSTR* aVersion)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aVersion)
+    return E_INVALIDARG;
+
   *aVersion = nullptr;
 
   if (IsDefunct())
diff --git a/accessible/src/windows/msaa/DocAccessibleWrap.cpp b/accessible/src/windows/msaa/DocAccessibleWrap.cpp
index 9539a78dbe56..cd366d3a6ccf 100644
--- a/accessible/src/windows/msaa/DocAccessibleWrap.cpp
+++ b/accessible/src/windows/msaa/DocAccessibleWrap.cpp
@@ -64,6 +64,9 @@ STDMETHODIMP_(ULONG) DocAccessibleWrap::Release()
 STDMETHODIMP
 DocAccessibleWrap::QueryInterface(REFIID iid, void** ppv)
 {
+  if (!ppv)
+    return E_INVALIDARG;
+
   *ppv = nullptr;
 
   if (IID_ISimpleDOMDocument != iid)
@@ -80,6 +83,9 @@ DocAccessibleWrap::get_URL(/* [out] */ BSTR __RPC_FAR *aURL)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aURL)
+    return E_INVALIDARG;
+
   *aURL = nullptr;
 
   nsAutoString URL;
@@ -101,6 +107,9 @@ DocAccessibleWrap::get_title( /* [out] */ BSTR __RPC_FAR *aTitle)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aTitle)
+    return E_INVALIDARG;
+
   *aTitle = nullptr;
 
   nsAutoString title;
@@ -119,6 +128,9 @@ DocAccessibleWrap::get_mimeType(/* [out] */ BSTR __RPC_FAR *aMimeType)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aMimeType)
+    return E_INVALIDARG;
+
   *aMimeType = nullptr;
 
   nsAutoString mimeType;
@@ -140,6 +152,9 @@ DocAccessibleWrap::get_docType(/* [out] */ BSTR __RPC_FAR *aDocType)
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aDocType)
+    return E_INVALIDARG;
+
   *aDocType = nullptr;
 
   nsAutoString docType;
@@ -162,6 +177,9 @@ DocAccessibleWrap::get_nameSpaceURIForID(/* [in] */  short aNameSpaceID,
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aNameSpaceURI)
+    return E_INVALIDARG;
+
   *aNameSpaceURI = nullptr;
 
   if (aNameSpaceID < 0)
@@ -188,6 +206,9 @@ DocAccessibleWrap::put_alternateViewMediaTypes( /* [in] */ BSTR __RPC_FAR *aComm
 {
   A11Y_TRYBLOCK_BEGIN
 
+  if (!aCommaSeparatedMediaTypes)
+    return E_INVALIDARG;
+
   *aCommaSeparatedMediaTypes = nullptr;
   return E_NOTIMPL;
 
@@ -199,6 +220,9 @@ DocAccessibleWrap::get_accValue(
       /* [optional][in] */ VARIANT varChild,
       /* [retval][out] */ BSTR __RPC_FAR *pszValue)
 {
+  if (!pszValue)
+    return E_INVALIDARG;
+
   // For backwards-compat, we still support old MSAA hack to provide URL in accValue
   *pszValue = nullptr;
   // Check for real value first