diff --git a/jsonpb/decode.go b/jsonpb/decode.go
index 8573830..7c6c5a5 100644
--- a/jsonpb/decode.go
+++ b/jsonpb/decode.go
@@ -474,7 +474,7 @@
 		if hasPrefixAndSuffix('"', in, '"') {
 			vd := fd.Enum().Values().ByName(protoreflect.Name(trimQuote(in)))
 			if vd == nil {
-				return v, fmt.Errorf("unknown value %v for enum %s", in, fd.Enum().FullName())
+				return v, fmt.Errorf("unknown value %q for enum %s", in, fd.Enum().FullName())
 			}
 			return protoreflect.ValueOfEnum(vd.Number()), nil
 		}