diff --git a/src/autonet/stdafx.h b/src/autonet/stdafx.h
index 3f7c7800f..0c337534c 100644
--- a/src/autonet/stdafx.h
+++ b/src/autonet/stdafx.h
@@ -3,7 +3,9 @@
 #include <math.h>
 #include <assert.h>
 #include <cctype>
-#define NOMINMAX
+#ifndef NOMINMAX
+  #define NOMINMAX
+#endif
 
 #ifndef _MSC_VER
   #include <stdlib.h>
diff --git a/src/autotesting/stdafx.h b/src/autotesting/stdafx.h
index 14acc27d3..03ed5c0e4 100644
--- a/src/autotesting/stdafx.h
+++ b/src/autotesting/stdafx.h
@@ -5,7 +5,9 @@
 // Currently this is only supported on MSVC
 #ifdef _MSC_VER
   #include <thread>
-  #define NOMINMAX
+  #ifndef NOMINMAX
+    #define NOMINMAX
+  #endif
 #endif
 	
 #ifndef _MSC_VER
@@ -18,4 +20,4 @@
 
 template<class T, int n>
 const char(&ArraySize(const T(&vals)[n]))[n];
-#define ARRAYCOUNT(x) sizeof(ArraySize(x))
\ No newline at end of file
+#define ARRAYCOUNT(x) sizeof(ArraySize(x))
diff --git a/src/autowiring/stdafx.h b/src/autowiring/stdafx.h
index 3d9784e03..b51770582 100644
--- a/src/autowiring/stdafx.h
+++ b/src/autowiring/stdafx.h
@@ -5,7 +5,9 @@
 // Currently this is only supported on MSVC
 #ifdef _MSC_VER
   #include <thread>
-  #define NOMINMAX
+  #ifndef NOMINMAX
+    #define NOMINMAX
+  #endif
 #endif
   
 #ifndef _MSC_VER