diff --git a/src/port/getopt.c b/src/port/getopt.c
index 655fef3b0c..2cca5a0673 100644
--- a/src/port/getopt.c
+++ b/src/port/getopt.c
@@ -72,7 +72,7 @@ int
 getopt(int nargc, char *const *nargv, const char *ostr)
 {
 	static char *place = EMSG;	/* option letter processing */
-	char	   *oli;			/* option letter list index */
+	const char *oli;			/* option letter list index */
 
 	if (!*place)
 	{							/* update scanning pointer */