diff --git a/hw/xbox/nv2a/pgraph/gl/debug.h b/hw/xbox/nv2a/pgraph/gl/debug.h
index 1220244da8..14f43eb394 100644
--- a/hw/xbox/nv2a/pgraph/gl/debug.h
+++ b/hw/xbox/nv2a/pgraph/gl/debug.h
@@ -32,10 +32,10 @@
 #include "config-host.h"
 
 void gl_debug_initialize(void);
-void gl_debug_message(bool cc, const char *fmt, ...);
-void gl_debug_group_begin(const char *fmt, ...);
+void gl_debug_message(bool cc, const char *fmt, ...) __attribute__ ((format (printf, 2, 3)));
+void gl_debug_group_begin(const char *fmt, ...) __attribute__ ((format (printf, 1, 2)));
 void gl_debug_group_end(void);
-void gl_debug_label(GLenum target, GLuint name, const char *fmt, ...);
+void gl_debug_label(GLenum target, GLuint name, const char *fmt, ...) __attribute__ ((format (printf, 3, 4)));
 void gl_debug_frame_terminator(void);
 
 # define NV2A_GL_DPRINTF(cc, format, ...) \