diff --git a/common/chat.cpp b/common/chat.cpp
index 955c42852a9be..3205cdf7bbc82 100644
--- a/common/chat.cpp
+++ b/common/chat.cpp
@@ -1830,7 +1830,7 @@ static common_chat_params common_chat_params_init_hermes_2_pro(const common_chat
                 // If thinking_forced_open, then we capture the </think> tag in the grammar,
                 // (important for required tool choice) and in the trigger's first capture (decides what is sent to the grammar)
                 std::string(data.thinking_forced_open ? "[\\s\\S]*?(</think>\\s*)" : "(?:<think>[\\s\\S]*?</think>\\s*)?") + (
-                    "(\\s*"
+                    "\\s*("
                     "(?:<tool_call>"
                     "|<function"
                     "|(?:```(?:json|xml)?\n\\s*)?(?:<function_call>|<tools>|<xml><json>|<response>)?"