include readtex.h instead of readtex.c
diff --git a/progs/demos/teapot.c b/progs/demos/teapot.c
index dd2eadf..67a64f9 100644
--- a/progs/demos/teapot.c
+++ b/progs/demos/teapot.c
@@ -16,7 +16,7 @@
 #endif
 
 #include <GL/glut.h>
-#include "readtex.c"
+#include "readtex.h"
 
 #ifdef XMESA
 #include "GL/xmesa.h"