diff --git a/gfx/public/nsTransform2D.h b/gfx/public/nsTransform2D.h
index 6612da2c099d..a2b9985aae4a 100644
--- a/gfx/public/nsTransform2D.h
+++ b/gfx/public/nsTransform2D.h
@@ -120,6 +120,20 @@ public:
   void GetTranslation(float *ptX, float *ptY) { *ptX = m20; *ptY = m21; }
   void GetTranslationCoord(nscoord *ptX, nscoord *ptY) { *ptX = NSToCoordRound(m20); *ptY = NSToCoordRound(m21); }
 
+ /**
+  * set the translation portion of this transform
+  *
+  * @param      tx, x translation
+  * @param      ty, y translation
+  * @exception
+  **/
+
+  void SetTranslation(float tX, float tY) {
+    m20 = tX;
+    m21 = tY;
+    type |= MG_2DTRANSLATION;
+  }
+
  /**
   * get the X translation portion of this transform
   *