diff --git a/internal/cbm/vendored/grammars/sql/scanner.c b/internal/cbm/vendored/grammars/sql/scanner.c
index 2277e4c65..fa3a9cb01 100644
--- a/internal/cbm/vendored/grammars/sql/scanner.c
+++ b/internal/cbm/vendored/grammars/sql/scanner.c
@@ -179,6 +179,7 @@ unsigned tree_sitter_sql_external_scanner_serialize(void *payload, char *buffer)
 
 void tree_sitter_sql_external_scanner_deserialize(void *payload, const char *buffer, unsigned length) {
   LexerState *state = (LexerState *)payload;
+  free(state->start_tag); /* deserialize is called repeatedly; free the prior tag first */
   state->start_tag = NULL;
   // A length of 1 can't exists.
   if (length > 1) {