diff --git a/cogl-matrix.h b/cogl-matrix.h
index 95ec92ffd..2c8003b50 100644
--- a/cogl-matrix.h
+++ b/cogl-matrix.h
@@ -65,6 +65,10 @@ typedef struct _CoglMatrix {
 
     /* Note: we may want to extend this later with private flags
      * and a cache of the inverse transform matrix. */
+    float   _padding0[16];
+    gulong  _padding1;
+    gulong  _padding2;
+    gulong  _padding3;
 } CoglMatrix;
 
 /**