diff --git a/dom/indexedDB/IDBKeyRange.cpp b/dom/indexedDB/IDBKeyRange.cpp
index ac8fe7a06e65..7038252a6047 100644
--- a/dom/indexedDB/IDBKeyRange.cpp
+++ b/dom/indexedDB/IDBKeyRange.cpp
@@ -22,8 +22,7 @@ namespace {
 nsresult
 GetKeyFromJSVal(JSContext* aCx,
                 JS::Handle<JS::Value> aVal,
-                Key& aKey,
-                bool aAllowUnset = false)
+                Key& aKey)
 {
   nsresult rv = aKey.SetFromJSVal(aCx, aVal);
   if (NS_FAILED(rv)) {
@@ -31,7 +30,7 @@ GetKeyFromJSVal(JSContext* aCx,
     return rv;
   }
 
-  if (aKey.IsUnset() && !aAllowUnset) {
+  if (aKey.IsUnset()) {
     return NS_ERROR_DOM_INDEXEDDB_DATA_ERR;
   }
 
@@ -347,39 +346,38 @@ IDBKeyRange::Includes(JSContext* aCx,
     return false;
   }
 
-  switch (Key::CompareKeys(Lower(), key)) {
-  case 1:
-    return false;
-  case 0:
-    // Identical keys.
-    if (LowerOpen()) {
+  MOZ_ASSERT(!(Lower().IsUnset() && Upper().IsUnset()));
+  MOZ_ASSERT_IF(IsOnly(),
+    !Lower().IsUnset() && !LowerOpen() &&
+    Lower() == Upper() && LowerOpen() == UpperOpen());
+
+  if (!Lower().IsUnset()) {
+    switch (Key::CompareKeys(Lower(), key)) {
+    case 1:
       return false;
+    case 0:
+      // Identical keys.
+      return !LowerOpen();
+    case -1:
+      if (IsOnly()) {
+        return false;
+      }
+      break;
+    default:
+      MOZ_CRASH();
     }
-    break;
-  case -1:
-    if (IsOnly()) {
-      return false;
-    }
-    break;
-  default:
-    MOZ_CRASH();
   }
 
-  if (!IsOnly()) {
+  if (!Upper().IsUnset()) {
     switch (Key::CompareKeys(key, Upper())) {
     case 1:
       return false;
     case 0:
       // Identical keys.
-      if (UpperOpen()) {
-        return false;
-      }
-      break;
+      return !UpperOpen();
     case -1:
       break;
     }
-  } else {
-    MOZ_ASSERT(key == Lower());
   }
 
   return true;
diff --git a/testing/web-platform/tests/IndexedDB/idbkeyrange-includes.htm b/testing/web-platform/tests/IndexedDB/idbkeyrange-includes.htm
index bfe9d2c482d6..6a05627463e0 100644
--- a/testing/web-platform/tests/IndexedDB/idbkeyrange-includes.htm
+++ b/testing/web-platform/tests/IndexedDB/idbkeyrange-includes.htm
@@ -5,7 +5,7 @@
 <script src=/resources/testharnessreport.js></script>
 <script>
 
-  test( function() {
+  test(function() {
     var closedRange = IDBKeyRange.bound(5, 20);
     assert_true(!!closedRange.includes, "IDBKeyRange has a .includes");
     assert_true(closedRange.includes(7), "in range");
@@ -17,17 +17,45 @@
                   "invalid key");
   }, "IDBKeyRange.includes() with a closed range");
 
-  test( function() {
+  test(function() {
     var openRange = IDBKeyRange.bound(5, 20, true, true);
     assert_false(openRange.includes(5) || openRange.includes(20),
                  "boundary points");
   }, "IDBKeyRange.includes() with an open range");
 
-  test( function() {
+  test(function() {
     var range = IDBKeyRange.only(42);
     assert_true(range.includes(42), "in range");
     assert_false(range.includes(1), "below range");
     assert_false(range.includes(9000), "above range");
   }, "IDBKeyRange.includes() with an only range");
 
+  test(function() {
+    var range = IDBKeyRange.lowerBound(5);
+    assert_false(range.includes(4), 'value before closed lower bound');
+    assert_true(range.includes(5), 'value at closed lower bound');
+    assert_true(range.includes(6), 'value after closed lower bound');
+  }, "IDBKeyRange.includes() with an closed lower-bounded range");
+
+  test(function() {
+    var range = IDBKeyRange.lowerBound(5, true);
+    assert_false(range.includes(4), 'value before open lower bound');
+    assert_false(range.includes(5), 'value at open lower bound');
+    assert_true(range.includes(6), 'value after open lower bound');
+  }, "IDBKeyRange.includes() with an open lower-bounded range");
+
+  test(function() {
+    var range = IDBKeyRange.upperBound(5);
+    assert_true(range.includes(4), 'value before closed upper bound');
+    assert_true(range.includes(5), 'value at closed upper bound');
+    assert_false(range.includes(6), 'value after closed upper bound');
+  }, "IDBKeyRange.includes() with an closed upper-bounded range");
+
+  test(function() {
+    var range = IDBKeyRange.upperBound(5, true);
+    assert_true(range.includes(4), 'value before open upper bound');
+    assert_false(range.includes(5), 'value at open upper bound');
+    assert_false(range.includes(6), 'value after open upper bound');
+  }, "IDBKeyRange.includes() with an open upper-bounded range");
+
 </script>