diff --git a/gfx/src/mac/nsImageMac.cpp b/gfx/src/mac/nsImageMac.cpp
index ee7e172b29b..6fde12e5abf 100644
--- a/gfx/src/mac/nsImageMac.cpp
+++ b/gfx/src/mac/nsImageMac.cpp
@@ -401,6 +401,7 @@ NS_IMETHODIMP nsImageMac::Draw(nsIRenderingContext &aContext, nsDrawingSurface a
           }
 
           ::DisposeGWorld(tempMaskGWorld);
+          free(scaledMaskBits);
         }
         else
         {
@@ -408,6 +409,7 @@ NS_IMETHODIMP nsImageMac::Draw(nsIRenderingContext &aContext, nsDrawingSurface a
         }
 
         ::DisposeGWorld(tempSrcGWorld);
+        free(scaledSrcBits);
       }
       else
       {