diff --git a/parser/internal/Cel.g4 b/parser/internal/Cel.g4
index 9b2c73954..f5d8c0c21 100644
--- a/parser/internal/Cel.g4
+++ b/parser/internal/Cel.g4
@@ -193,8 +193,8 @@ NUM_UINT
 STRING
   : '"' (ESC_SEQ | ~('\\'|'"'|'\n'|'\r'))* '"'
   | '\'' (ESC_SEQ | ~('\\'|'\''|'\n'|'\r'))* '\''
-  | '"""' (ESC_SEQ | ~('\\'))*? '"""'
-  | '\'\'\'' (ESC_SEQ | ~('\\'))*? '\'\'\''
+  | '"""' (ESC_SEQ | '\\' . | ~('\\'))*? '"""'
+  | '\'\'\'' (ESC_SEQ | '\\' . | ~('\\'))*? '\'\'\''
   | RAW '"' ~('"'|'\n'|'\r')* '"'
   | RAW '\'' ~('\''|'\n'|'\r')* '\''
   | RAW '"""' .*? '"""'