diff --git a/xpcom/io/nsStreamUtils.cpp b/xpcom/io/nsStreamUtils.cpp
index e38c037302e7..e23cda49e07a 100644
--- a/xpcom/io/nsStreamUtils.cpp
+++ b/xpcom/io/nsStreamUtils.cpp
@@ -853,6 +853,10 @@ nsresult
 NS_CloneInputStream(nsIInputStream* aSource, nsIInputStream** aCloneOut,
                     nsIInputStream** aReplacementOut)
 {
+  if (NS_WARN_IF(!aSource)) {
+    return NS_ERROR_FAILURE;
+  }
+
   // Attempt to perform the clone directly on the source stream
   nsCOMPtr<nsICloneableInputStream> cloneable = do_QueryInterface(aSource);
   if (cloneable && cloneable->GetCloneable()) {
diff --git a/xpcom/tests/gtest/TestCloneInputStream.cpp b/xpcom/tests/gtest/TestCloneInputStream.cpp
index d9b2dc28dde2..633d207988f9 100644
--- a/xpcom/tests/gtest/TestCloneInputStream.cpp
+++ b/xpcom/tests/gtest/TestCloneInputStream.cpp
@@ -12,6 +12,14 @@
 #include "nsStreamUtils.h"
 #include "nsStringStream.h"
 
+TEST(CloneInputStream, InvalidInput)
+{
+  nsCOMPtr<nsIInputStream> clone;
+  nsresult rv = NS_CloneInputStream(nullptr, getter_AddRefs(clone));
+  ASSERT_TRUE(NS_FAILED(rv));
+  ASSERT_FALSE(clone);
+}
+
 TEST(CloneInputStream, CloneableInput)
 {
   nsTArray<char> inputData;