diff --git a/direct/src/plugin/p3dCert.cxx b/direct/src/plugin/p3dCert.cxx
index 1800a2f4db..528bde0d49 100644
--- a/direct/src/plugin/p3dCert.cxx
+++ b/direct/src/plugin/p3dCert.cxx
@@ -16,10 +16,10 @@
 #include "wstring_encode.h"
 #include "mkdir_complete.h"
 
-#include <Fl/Fl_Box.H>
-#include <Fl/Fl_Button.H>
-#include <Fl/Fl_Return_Button.H>
-#include <Fl/Fl_Text_Display.H>
+#include <FL/Fl_Box.H>
+#include <FL/Fl_Button.H>
+#include <FL/Fl_Return_Button.H>
+#include <FL/Fl_Text_Display.H>
 
 #include <cassert>
 #include <sys/types.h>
diff --git a/direct/src/plugin/p3dCert.h b/direct/src/plugin/p3dCert.h
index 641a362147..dd434409b6 100644
--- a/direct/src/plugin/p3dCert.h
+++ b/direct/src/plugin/p3dCert.h
@@ -15,8 +15,8 @@
 #ifndef P3DCERT_H
 #define P3DCERT_H
 
-#include <Fl/Fl.H>
-#include <Fl/Fl_Window.H>
+#include <FL/Fl.H>
+#include <FL/Fl_Window.H>
 
 #define OPENSSL_NO_KRB5
 #include "openssl/x509.h"
diff --git a/makepanda/makepanda.py b/makepanda/makepanda.py
index 2da1aea515..56d8cdc4cc 100755
--- a/makepanda/makepanda.py
+++ b/makepanda/makepanda.py
@@ -749,8 +749,8 @@ if (COMPILER=="GCC"):
         SmartPkgEnable("PYTHON",    "", SDK["PYTHONVERSION"], (SDK["PYTHONVERSION"], SDK["PYTHONVERSION"] + "/Python.h"), tool = SDK["PYTHONVERSION"] + "-config", framework = "Python")
 
     if (RTDIST):
-        SmartPkgEnable("WX",    tool = "wx-config")
-        SmartPkgEnable("FLTK", "", ("fltk"), ("Fl/Fl.H"), tool = "fltk-config")
+        SmartPkgEnable("WX", tool = "wx-config")
+        SmartPkgEnable("FLTK", "", ("fltk"), ("FL/Fl.H"), tool = "fltk-config")
 
     if GetTarget() != 'darwin':
         # CgGL is covered by the Cg framework, and we don't need X11 components on OSX