diff --git a/Graphics/drawPost.cpp b/Graphics/drawPost.cpp
index decb6c91b09bef4cae2c80d1097cdace08f79464..06bfd275e264ccfacf1caa963b3a289929ddbda1 100644
--- a/Graphics/drawPost.cpp
+++ b/Graphics/drawPost.cpp
@@ -19,7 +19,7 @@
 
 #if defined(HAVE_FLTK)
 #include <FL/Fl.H>
-#include <FL/gl.H>
+#include <FL/gl.h>
 #endif
 
 static void drawArrays(drawContext *ctx, PView *p, VertexArray *va, GLint type,