Don't try to copy past end of field string

1 files changed, 5 insertions, 1 deletions

diff --git a/fref.lex b/fref.lex
index e57eb01..2eaa19d 100644
--- a/fref.lex
+++ b/fref.lex
@@ -124,7 +124,11 @@ field()
 	yytext[strcspn(yytext, "\n")] = 0;
 
 	/* Fill corresponding field. */
-	#define FI(s,m) if(strncmp(yytext,s,2) == 0 && (yytext += 3)){	\
+	#define FI(s,m) if(strncmp(yytext,s,2) == 0){			\
+		/* Don't copy empty field. */				\
+		if(strlen(yytext) < 3)					\
+			return;						\
+		yytext += 3;						\
 		strcpy(m, yytext);					\
 		return;							\
 	}