diff --git a/glslUtil.c b/glslUtil.c
index 892f6eb..adc4981 100644
--- a/glslUtil.c
+++ b/glslUtil.c
@@ -200,7 +200,7 @@ void guMatrix4x4To3x3(guMatrix3x3 *out, const guMatrix4x4 *in)
     int i;
     for (i = 0; i < 3; i++)
     {
-        memcpy(&(*out)[i], &(*in)[i], sizeof((*out)[0][0] * 3));
+        memcpy(&(*out)[i], &(*in)[i], sizeof((*out)[0][0]) * 3);
     }
 }