diff --git a/gfx/src/FilterSupport.cpp b/gfx/src/FilterSupport.cpp
index c06a4b1ec0e..2fc3943c8ff 100644
--- a/gfx/src/FilterSupport.cpp
+++ b/gfx/src/FilterSupport.cpp
@@ -1568,6 +1568,27 @@ FilterPrimitiveDescription::operator=(const FilterPrimitiveDescription& aOther)
   return *this;
 }
 
+bool
+FilterPrimitiveDescription::operator==(const FilterPrimitiveDescription& aOther) const
+{
+  return mType == aOther.mType &&
+    mFilterPrimitiveSubregion.IsEqualInterior(aOther.mFilterPrimitiveSubregion) &&
+    mOutputColorSpace == aOther.mOutputColorSpace &&
+    mIsTainted == aOther.mIsTainted &&
+    mInputPrimitives == aOther.mInputPrimitives &&
+    mInputColorSpaces == aOther.mInputColorSpaces &&
+    mAttributes == aOther.mAttributes;
+}
+
+// FilterDescription
+
+bool
+FilterDescription::operator==(const FilterDescription& aOther) const
+{
+  return mFilterSpaceBounds.IsEqualInterior(aOther.mFilterSpaceBounds) &&
+    mPrimitives == aOther.mPrimitives;
+}
+
 // AttributeMap
 
 // A class that wraps different types for easy storage in a hashtable. Only
diff --git a/gfx/src/FilterSupport.h b/gfx/src/FilterSupport.h
index 0c3a4d2129e..f080c7d72e0 100644
--- a/gfx/src/FilterSupport.h
+++ b/gfx/src/FilterSupport.h
@@ -337,6 +337,12 @@ public:
     mOutputColorSpace = aColorSpace;
   }
 
+  bool operator==(const FilterPrimitiveDescription& aOther) const;
+  bool operator!=(const FilterPrimitiveDescription& aOther) const
+  {
+    return !(*this == aOther);
+  }
+
 private:
   PrimitiveType mType;
   AttributeMap mAttributes;
@@ -360,6 +366,12 @@ struct FilterDescription MOZ_FINAL {
    , mFilterSpaceBounds(aFilterSpaceBounds)
   {}
 
+  bool operator==(const FilterDescription& aOther) const;
+  bool operator!=(const FilterDescription& aOther) const
+  {
+    return !(*this == aOther);
+  }
+
   nsTArray<FilterPrimitiveDescription> mPrimitives;
   IntRect mFilterSpaceBounds;
 };