Index: sys/boot/common/part.c
===================================================================
--- sys/boot/common/part.c
+++ sys/boot/common/part.c
@@ -301,12 +301,12 @@
 			}
 		}
 	}
-	DEBUG("GPT detected");
 	if (pri == 0 && sec == 0) {
 		/* Both primary and backup tables are invalid. */
 		table->type = PTABLE_NONE;
 		goto out;
 	}
+	DEBUG("GPT detected");
 	size = MIN(hdr.hdr_entries * hdr.hdr_entsz,
 	    MAXTBLSZ * table->sectorsize);
 	for (i = 0; i < size / hdr.hdr_entsz; i++) {
@@ -635,6 +635,11 @@
 	if (buf[DOSMAGICOFFSET] != 0x55 ||
 	    buf[DOSMAGICOFFSET + 1] != 0xaa) {
 		DEBUG("magic sequence not found");
+#if defined(LOADER_GPT_SUPPORT)
+		/* There is no PMBR, check that we have backup GPT */
+		table->type = PTABLE_GPT;
+		table = ptable_gptread(table, dev, dread);
+#endif
 		goto out;
 	}
 	/* Check that we have PMBR. Also do some validation. */
Index: sys/geom/part/g_part_gpt.c
===================================================================
--- sys/geom/part/g_part_gpt.c
+++ sys/geom/part/g_part_gpt.c
@@ -828,17 +828,17 @@
 			pri = G_PART_PROBE_PRI_HIGH;
 	}
 	g_free(buf);
-	if (res != DOSMAGIC) 
-		return (ENXIO);
 
 	/* Check that there's a primary header. */
-	buf = g_read_data(cp, pp->sectorsize, pp->sectorsize, &error);
-	if (buf == NULL)
-		return (error);
-	res = memcmp(buf, GPT_HDR_SIG, 8);
-	g_free(buf);
-	if (res == 0)
-		return (pri);
+	if (res == DOSMAGIC) {
+		buf = g_read_data(cp, pp->sectorsize, pp->sectorsize, &error);
+		if (buf == NULL)
+			return (error);
+		res = memcmp(buf, GPT_HDR_SIG, 8);
+		g_free(buf);
+		if (res == 0)
+			return (pri);
+	}
 
 	/* No primary? Check that there's a secondary. */
 	buf = g_read_data(cp, pp->mediasize - pp->sectorsize, pp->sectorsize,