diff --git a/src/truetype/ttgxvar.c b/src/truetype/ttgxvar.c
index ad4f266b2..78b80782a 100644
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -2141,7 +2141,8 @@
                                          outerIndex,
                                          innerIndex );
 
-	  v += delta << 2;
+          /* Convert to 16.16 format before adding. */
+	  v += delta * 4;
 
 	  /* Clamp value range. */
 	  v = v >=  0x10000L ?  0x10000 : v;