diff --git a/wscript b/wscript
index 5ad93de453..f5b7629b3b 100755
--- a/wscript
+++ b/wscript
@@ -723,7 +723,7 @@ class OptionItem(Item):
         print("{} = {}".format(self.data["name"], value))
 
     def _do_append_test_cppflags(self, conf, name, state):
-        conf.env.append_value("TEST_" + name.upper() + "_CPPFLAGS", state)
+        conf.env.append_value("TEST_" + name.upper().replace("-", "_") + "_CPPFLAGS", state)
 
     def _append_test_cppflags(self, conf, cic, value, arg):
         self._do_append_test_cppflags(conf, arg, value)