diff --git a/src/cairo-gl-operand.c b/src/cairo-gl-operand.c
index ddff5e7..0547f04 100644
--- a/src/cairo-gl-operand.c
+++ b/src/cairo-gl-operand.c
@@ -311,8 +311,8 @@ void
 _cairo_gl_operand_translate (cairo_gl_operand_t *operand,
 			     double tx, double ty)
 {
-    operand->texture.attributes.matrix.x0 -= tx * operand->texture.attributes.matrix.xx;
-    operand->texture.attributes.matrix.y0 -= ty * operand->texture.attributes.matrix.yy;
+    operand->texture.attributes.matrix.x0 += tx * operand->texture.attributes.matrix.xx;
+    operand->texture.attributes.matrix.y0 += ty * operand->texture.attributes.matrix.yy;
 }
 
 static cairo_status_t