diff --git a/src/drivers/GDI/Fl_GDI_Graphics_Driver_arci.cxx b/src/drivers/GDI/Fl_GDI_Graphics_Driver_arci.cxx
index 83f7fbeda..77753139f 100644
--- a/src/drivers/GDI/Fl_GDI_Graphics_Driver_arci.cxx
+++ b/src/drivers/GDI/Fl_GDI_Graphics_Driver_arci.cxx
@@ -33,7 +33,7 @@
 #include "Fl_GDI_Graphics_Driver.H"
 
 #include <FL/math.h>
-#include <FL/x.h>
+#include <FL/x.H>
 
 void Fl_GDI_Graphics_Driver::arc(int x,int y,int w,int h,double a1,double a2) {
   if (w <= 0 || h <= 0) return;
diff --git a/src/drivers/WinAPI/Fl_WinAPI_Printer_Driver.cxx b/src/drivers/WinAPI/Fl_WinAPI_Printer_Driver.cxx
index 03e94bee2..2c318d0b4 100644
--- a/src/drivers/WinAPI/Fl_WinAPI_Printer_Driver.cxx
+++ b/src/drivers/WinAPI/Fl_WinAPI_Printer_Driver.cxx
@@ -23,7 +23,7 @@
 #include <FL/fl_ask.H>
 #include <FL/math.h>
 #include <FL/fl_draw.H>
-#include <Commdlg.h>
+#include <commdlg.h>
 
 extern HWND fl_window;