diff --git a/lldb/packages/Python/lldbsuite/test/dotest.py b/lldb/packages/Python/lldbsuite/test/dotest.py
index e30d5490bea22..643077405e2ea 100644
--- a/lldb/packages/Python/lldbsuite/test/dotest.py
+++ b/lldb/packages/Python/lldbsuite/test/dotest.py
@@ -300,7 +300,8 @@ def parseOptionsAndInitTestdirs():
             configuration.libcxx_include_target_dir = args.libcxx_include_target_dir
             configuration.libcxx_library_dir = args.libcxx_library_dir
 
-    configuration.cmake_build_type = args.cmake_build_type.lower()
+    if args.cmake_build_type:
+        configuration.cmake_build_type = args.cmake_build_type.lower()
 
     if args.channels:
         lldbtest_config.channels = args.channels