diff --git a/src/options.ts b/src/options.ts
index d8c9a1e..3d29460 100644
--- a/src/options.ts
+++ b/src/options.ts
@@ -24,7 +24,7 @@ export const defaultOptions: IOptions = {
   escapeChar: "\\",
   optionalSegmentEndChar: ")",
   optionalSegmentStartChar: "(",
-  segmentNameCharset: "a-zA-Z0-9",
+  segmentNameCharset: "a-zA-Z0-9_",
   segmentNameStartChar: ":",
   segmentValueCharset: "a-zA-Z0-9-_~ %",
   wildcardChar: "*",