diff --git a/indra/cmake/run_build_test.py b/indra/cmake/run_build_test.py
index a79d09a9eabf6a386a923dae6ed34b921813c768..fdbb0a75f7128fcb33c3a7e12bbf43460f7fe336 100755
--- a/indra/cmake/run_build_test.py
+++ b/indra/cmake/run_build_test.py
@@ -78,7 +78,7 @@ def main(command, libpath=[], vars={}):
         # No idea what the right pathname might be! But only crump if this
         # feature is requested.
         if libpath:
-            raise NotImplemented("run_build_test: unknown platform %s" % sys.platform)
+            raise RuntimeError("run_build_test: unknown platform %s" % sys.platform)
         lpvars = []
     for var in lpvars:
         # Split the existing path. Bear in mind that the variable in question