diff --git a/sbin/geom/class/part/geom_part.c b/sbin/geom/class/part/geom_part.c
index fc179a4ccccf..db3c5e9515ee 100644
--- a/sbin/geom/class/part/geom_part.c
+++ b/sbin/geom/class/part/geom_part.c
@@ -274,8 +274,18 @@ gpart_autofill(struct gctl_req *req)
 	error = geom_gettree(&mesh);
 	if (error)
 		return (error);
-	cp = find_class(&mesh, gctl_get_ascii(req, "class"));
-	gp = find_geom(cp, gctl_get_ascii(req, "geom"));
+	s = gctl_get_ascii(req, "class");
+	if (s == NULL)
+		abort();
+	cp = find_class(&mesh, s);
+	if (cp == NULL)
+		errx(EXIT_FAILURE, "Class %s not found.", s);
+	s = gctl_get_ascii(req, "geom");
+	if (s == NULL)
+		abort();
+	gp = find_geom(cp, s);
+	if (gp == NULL)
+		errx(EXIT_FAILURE, "No such geom: %s.", s);
 	first = atoll(find_geomcfg(gp, "first"));
 	last = atoll(find_geomcfg(gp, "last"));
 	grade = ~0ULL;
@@ -536,6 +546,8 @@ gpart_write_partcode(struct gctl_req *req, int idx, void *code, ssize_t size)
 		errx(EXIT_FAILURE, "Class %s not found.", s);
 	}
 	s = gctl_get_ascii(req, "geom");
+	if (s == NULL)
+		abort();
 	gp = find_geom(classp, s);
 	if (gp == NULL)
 		errx(EXIT_FAILURE, "No such geom: %s.", s);