diff --git a/re2/tostring.cc b/re2/tostring.cc
index c59d4d9..0230c8c 100644
--- a/re2/tostring.cc
+++ b/re2/tostring.cc
@@ -156,12 +156,14 @@
       break;
 
     case kRegexpLiteral:
-      AppendLiteral(t_, re->rune(), re->parse_flags() & Regexp::FoldCase);
+      AppendLiteral(t_, re->rune(),
+                    (re->parse_flags() & Regexp::FoldCase) != 0);
       break;
 
     case kRegexpLiteralString:
       for (int i = 0; i < re->nrunes(); i++)
-        AppendLiteral(t_, re->runes()[i], re->parse_flags() & Regexp::FoldCase);
+        AppendLiteral(t_, re->runes()[i],
+                      (re->parse_flags() & Regexp::FoldCase) != 0);
       if (prec < PrecConcat)
         t_->append(")");
       break;