diff --git a/t/test-lib.sh b/t/test-lib.sh
index 007d7b20d..7f4cb67c0 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -383,6 +383,10 @@ test_done () {
 	case "$test_failure" in
 	0)
 		# Maybe print SKIP message
+		if test -n "$skip_all" && test $test_count -gt 0
+		then
+			error "Can't use skip_all after running some tests"
+		fi
 		[ -z "$skip_all" ] || skip_all=" # SKIP $skip_all"
 
 		if test $test_external_has_tap -eq 0