diff --git a/src/auth/mod.rs b/src/auth/mod.rs
index 4226aae..63a74e1 100644
--- a/src/auth/mod.rs
+++ b/src/auth/mod.rs
@@ -24,7 +24,7 @@ pub(crate) fn parse_u32(input: &str) -> Result<u32, std::num::ParseIntError> {
 }
 
 pub(crate) fn base64_char(input: &str) -> IResult<&str, &str> {
-    nom::bytes::complete::is_a("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=")(
+    nom::bytes::complete::is_a("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_=")(
         input,
     )
 }