diff --git a/04_mats_and_vecs/main.cpp b/04_mats_and_vecs/main.cpp
index 12b4f04..87aa0eb 100644
--- a/04_mats_and_vecs/main.cpp
+++ b/04_mats_and_vecs/main.cpp
@@ -101,7 +101,7 @@ int main() {
   if ( GL_TRUE != params ) {
     fprintf( stderr, "ERROR: could not link shader programme GL index %i\n", shader_programme );
     print_programme_info_log( shader_programme );
-    return false;
+    return 1;
   }
 
   GLfloat matrix[] = {