diff --git a/testsuite/lib/stap_run.exp b/testsuite/lib/stap_run.exp
index dab8e06..dc03d65 100644
--- a/testsuite/lib/stap_run.exp
+++ b/testsuite/lib/stap_run.exp
@@ -90,8 +90,14 @@ proc stap_run { TEST_NAME {LOAD_GEN_FUNCTION ""} {OUTPUT_CHECK_STRING ""} args }
 			-re $warning_regexp {
 			    set probe_errors $expect_out(1,string)
 			    set skipped_probes $expect_out(2,string)}
+			default {
+			    fail "$TEST_NAME unexpected output (after passing output)"
+			}
 		    }
 		}
+		default {
+		    fail "$TEST_NAME unexpected output"
+		}
 		timeout { 
                     fail "$TEST_NAME shutdown (timeout)"
                     kill -INT -[exp_pid]