1 files changed, 1 insertions, 1 deletions
diff --git a/tkzinc.m4 b/tkzinc.m4
index e1fde7e..b18f25f 100644
--- a/tkzinc.m4
+++ b/tkzinc.m4
@@ -56,7 +56,7 @@ AC_DEFUN(ZINC_ENABLE_GL, [
 	    GL_LIBS=-lopengl32
 	else
  	  GL_LIBS="-lGL"
- 	  GL_INCLUDES='/usr/include'
+ 	  GL_INCLUDES='-I/usr/include'
         fi
 
  	AC_DEFINE(GL)