diff --git a/BuildBotLib/basemodule.py b/BuildBotLib/basemodule.py
index fe39a9c..0ad0a72 100644
--- a/BuildBotLib/basemodule.py
+++ b/BuildBotLib/basemodule.py
@@ -97,7 +97,7 @@ class BaseModule:
 
         return 'make'
 
-    def makeTarget(self, target, cxxFlags=[]):
+    def makeTarget(self, target, cxxFlags=None):
         command = [self.make()]
         return command + [target]
 
diff --git a/BuildBotLib/cmake.py b/BuildBotLib/cmake.py
index cda839b..50f8526 100644
--- a/BuildBotLib/cmake.py
+++ b/BuildBotLib/cmake.py
@@ -15,7 +15,7 @@ class CMake(Make):
     def makePrefix(self):
         return "C"
 
-    def makeTarget(self, target, cxxFlags=[]):
+    def makeTarget(self, target, cxxFlags=None):
         command = 'cmake --build cmake_build --config Release'
 
         if len(target):
@@ -25,7 +25,9 @@ class CMake(Make):
             if cpus:
                 command += ' --parallel ' + str(cpus)
 
-        cxx = cxxFlags
+        cxx = []
+        if cxxFlags is not None:
+            cxx += cxxFlags
 
         if self.isiOS(''):
             cxx += ['-allowProvisioningUpdates']