diff --git a/lib/asn1/main.c b/lib/asn1/main.c
index fcf45946e..2cabcc209 100644
--- a/lib/asn1/main.c
+++ b/lib/asn1/main.c
@@ -57,8 +57,8 @@ int
 main(int argc, char **argv)
 {
     int ret;
-    char *file;
-    char *name = NULL;
+    const char *file;
+    const char *name = NULL;
     int optind = 0;
 
     setprogname(argv[0]);