diff --git a/GL/glx/singlesize.h b/GL/glx/singlesize.h
index bde62092c..4804a9982 100644
--- a/GL/glx/singlesize.h
+++ b/GL/glx/singlesize.h
@@ -41,6 +41,8 @@
 **
 */
 
+#include "indirect_size.h"
+
 extern GLint __glReadPixels_size(GLenum format, GLenum type,
 				 GLint width, GLint height);
 extern GLint __glGetTexEnvfv_size(GLenum pname);