diff --git a/t/test-lib.sh b/t/test-lib.sh
index d685858afd..21ebe95139 100644
--- a/t/test-lib.sh
+++ b/t/test-lib.sh
@@ -317,6 +317,16 @@ say () {
 	say_color info "$*"
 }
 
+if test -n "$HARNESS_ACTIVE"
+then
+	if test "$verbose" = t || test -n "$verbose_only"
+	then
+		printf 'Bail out! %s\n' \
+		 'verbose mode forbidden under TAP harness; try --verbose-log'
+		exit 1
+	fi
+fi
+
 test "${test_description}" != "" ||
 error "Test script did not set test_description."