diff --git a/tools/vs.py b/tools/vs.py
index bd1c7a4b2469c30d2735124355ca86e1ea519837..958d166d2d8620e8f5e93a5ce7267d86b87a3bf1 100644
--- a/tools/vs.py
+++ b/tools/vs.py
@@ -108,7 +108,14 @@ def VSProject(target, script, program):
 
     # write cppdefinitons flags
     if building.Env.has_key('CPPDEFINES'):
-        definitions = ';'.join(building.Env['CPPDEFINES'])
+        CPPDEFINES = building.Env['CPPDEFINES']
+        definitions = []
+        if type(CPPDEFINES[0]) == type(()):
+            for item in CPPDEFINES:
+                definitions += [i for i in item]
+            definitions = ';'.join(definitions)
+        else:
+            definitions = ';'.join(building.Env['CPPDEFINES'])
         elem.set('PreprocessorDefinitions', definitions)
     # write link flags