diff --git a/include/wx/gtk/dc.h b/include/wx/gtk/dc.h
index 1bc4d18c56..84c79d7353 100644
--- a/include/wx/gtk/dc.h
+++ b/include/wx/gtk/dc.h
@@ -25,6 +25,7 @@ class wxDC;
 // constants
 //-----------------------------------------------------------------------------
 
+#ifndef MM_TEXT
 #define MM_TEXT         0
 #define MM_ISOTROPIC    1
 #define MM_ANISOTROPIC  2
@@ -33,6 +34,7 @@ class wxDC;
 #define MM_TWIPS        5
 #define MM_POINTS       6
 #define MM_METRIC       7
+#endif
 
 //-----------------------------------------------------------------------------
 // wxDC
diff --git a/include/wx/gtk1/dc.h b/include/wx/gtk1/dc.h
index 1bc4d18c56..84c79d7353 100644
--- a/include/wx/gtk1/dc.h
+++ b/include/wx/gtk1/dc.h
@@ -25,6 +25,7 @@ class wxDC;
 // constants
 //-----------------------------------------------------------------------------
 
+#ifndef MM_TEXT
 #define MM_TEXT         0
 #define MM_ISOTROPIC    1
 #define MM_ANISOTROPIC  2
@@ -33,6 +34,7 @@ class wxDC;
 #define MM_TWIPS        5
 #define MM_POINTS       6
 #define MM_METRIC       7
+#endif
 
 //-----------------------------------------------------------------------------
 // wxDC
diff --git a/include/wx/mgl/dc.h b/include/wx/mgl/dc.h
index 7ac52ee1f5..db07868a65 100644
--- a/include/wx/mgl/dc.h
+++ b/include/wx/mgl/dc.h
@@ -28,6 +28,7 @@ class WXDLLEXPORT wxDC;
 // constants
 //-----------------------------------------------------------------------------
 
+#ifndef MM_TEXT
 #define MM_TEXT         0
 #define MM_ISOTROPIC    1
 #define MM_ANISOTROPIC  2
@@ -36,6 +37,7 @@ class WXDLLEXPORT wxDC;
 #define MM_TWIPS        5
 #define MM_POINTS       6
 #define MM_METRIC       7
+#endif
 
 //-----------------------------------------------------------------------------
 // wxDC