diff --git a/src/protocol/lexer.rs b/src/protocol/lexer.rs
index afd0bc50f80ce32e28cbe8fe6b63a6371eeab2c9..fb8e62e99acaf36f8bbe7e5396c2fd2f4754edb4 100644
--- a/src/protocol/lexer.rs
+++ b/src/protocol/lexer.rs
@@ -419,7 +419,7 @@ impl Lexer<'_> {
         let mut ns_ident = self.consume_ident()?;
         let mut num_namespaces = 1;
         while self.has_string(b"::") {
-            self.consume_string(b"::");
+            self.consume_string(b"::")?;
             if num_namespaces >= MAX_NAMESPACES {
                 return Err(self.error_at_pos("Too many namespaces in identifier"));
             }