diff --git a/tools/test-runner.c b/tools/test-runner.c
index 2db730f1..1d7ee304 100644
--- a/tools/test-runner.c
+++ b/tools/test-runner.c
@@ -1664,6 +1664,7 @@ static void run_tests(void)
 		if (debug_filter[0] != '\0') {
 			enable_debug = true;
 			l_debug_enable(debug_filter);
+			setenv("HWSIM_DEBUG", "", true);
 		}
 	}