diff --git a/layout/generic/nsLineLayout.h b/layout/generic/nsLineLayout.h
index ae605f5102c3..4b451253af40 100644
--- a/layout/generic/nsLineLayout.h
+++ b/layout/generic/nsLineLayout.h
@@ -288,7 +288,7 @@ protected:
 
   PRUint8 mPlacedFloaters;
   PRInt32 mTotalPlacedFrames;
-  nsVoidArray mWordFrames;
+  nsAutoVoidArray mWordFrames;
 
   nscoord mTopEdge;
   nscoord mBottomEdge;
diff --git a/layout/html/base/src/nsLineLayout.h b/layout/html/base/src/nsLineLayout.h
index ae605f5102c3..4b451253af40 100644
--- a/layout/html/base/src/nsLineLayout.h
+++ b/layout/html/base/src/nsLineLayout.h
@@ -288,7 +288,7 @@ protected:
 
   PRUint8 mPlacedFloaters;
   PRInt32 mTotalPlacedFrames;
-  nsVoidArray mWordFrames;
+  nsAutoVoidArray mWordFrames;
 
   nscoord mTopEdge;
   nscoord mBottomEdge;