diff --git a/test/fractals.cxx b/test/fractals.cxx
index efc47777e..46d1fcb94 100644
--- a/test/fractals.cxx
+++ b/test/fractals.cxx
@@ -64,7 +64,7 @@ int main(int, char**) {
  */
 
 #include <FL/glut.H>
-#include <FL/glu.H>
+#include <FL/glu.h>
 
 #include <stdio.h>
 #include <stdlib.h>
diff --git a/test/fracviewer.cxx b/test/fracviewer.cxx
index 8e9ab8771..bc45cc045 100644
--- a/test/fracviewer.cxx
+++ b/test/fracviewer.cxx
@@ -16,7 +16,7 @@
 
 #if HAVE_GL && HAVE_GL_GLU_H
 #  include <FL/glut.H>
-#  include <FL/glu.H>
+#  include <FL/glu.h>
 
 #  include <stdio.h>
 #  include <stdlib.h>