diff --git a/mdit_py_plugins/texmath/index.py b/mdit_py_plugins/texmath/index.py
index 63a169d..c00e70e 100644
--- a/mdit_py_plugins/texmath/index.py
+++ b/mdit_py_plugins/texmath/index.py
@@ -152,7 +152,7 @@ def _func(state: StateBlock, begLine: int, endLine: int, silent: bool) -> bool:
 def dollar_pre(src: str, beg: int) -> bool:
     prv = charCodeAt(src[beg - 1], 0) if beg > 0 else False
     return (
-        (not prv) or prv != 0x5C and (prv < 0x30 or prv > 0x39)  # no backslash,
+        (not prv) or (prv != 0x5C and (prv < 0x30 or prv > 0x39))  # no backslash,
     )  # no decimal digit .. before opening '$'