diff --git a/src/parser.pegjs b/src/parser.pegjs
index 8e2a857f1d9e8da289d43f578ddc5c349bd7ed6a..c3a11935997d74db7c8dfe51718b91146cb53fcb 100644
--- a/src/parser.pegjs
+++ b/src/parser.pegjs
@@ -335,7 +335,7 @@ urlContent
 urlContentPart
 	= urlBracketPair
 	/ [.,] &urlContentPart // last char is neither "." nor ",".
-	/ [a-z0-9/:%#@$&?!~=+-]i
+	/ [a-z0-9_/:%#@$&?!~=+-]i
 
 urlBracketPair
 	= "(" urlContentPart* ")"