diff --git a/neo/idlib/Lexer.h b/neo/idlib/Lexer.h
index ea73cf1..9ff408c 100644
--- a/neo/idlib/Lexer.h
+++ b/neo/idlib/Lexer.h
@@ -129,7 +129,7 @@ typedef enum {
 // punctuation
 typedef struct punctuation_s
 {
-	char *p;						// punctuation character(s)
+	const char *p;						// punctuation character(s)
 	int n;							// punctuation id
 } punctuation_t;