diff --git a/src/if-options.c b/src/if-options.c
index 7b445f45..0ec71a43 100644
--- a/src/if-options.c
+++ b/src/if-options.c
@@ -2106,7 +2106,7 @@ parse_option(struct dhcpcd_ctx *ctx, const char *ifname, struct if_options *ifo,
 		}
 		/* variable */
 		if (!fp) {
-			if (!(t & OT_OPTION)) {
+			if (!(t & OT_OPTION) || opt != O_ENCAP) {
 				logerrx("type %s requires a variable name",
 				    arg);
 				return -1;
@@ -2117,7 +2117,14 @@ parse_option(struct dhcpcd_ctx *ctx, const char *ifname, struct if_options *ifo,
 			fp = strwhite(arg);
 			if (fp)
 				*fp++ = '\0';
-			if (strcasecmp(arg, "reserved")) {
+			if (arg == NULL) {
+				if (!(t & OT_OPTION) || opt != O_ENCAP) {
+					logerrx(
+					    "type requires a variable name");
+					return -1;
+				}
+				np = NULL;
+			} else if (strcasecmp(arg, "reserved")) {
 				np = strdup(arg);
 				if (np == NULL) {
 					logerr(__func__);