diff --git a/src/fprime/util/cli.py b/src/fprime/util/cli.py
index eceb5f8d..3037a053 100644
--- a/src/fprime/util/cli.py
+++ b/src/fprime/util/cli.py
@@ -219,7 +219,7 @@ def validate(parsed, unknown):
     if parsed.command == "generate":
         d_args = {
             match.group(1): match.group(2)
-            for match in [CMAKE_REG.match(arg) for arg in unknown]
+            for match in [CMAKE_REG.match(arg) for arg in unknown] if match is not None
         }
         cmake_args.update(d_args)
         unknown = [arg for arg in unknown if not CMAKE_REG.match(arg)]