diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 0ef96a29dd85..ddc012f04123 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -2382,6 +2382,11 @@ pmap_init(void)
 		KASSERT(MAXPAGESIZES > 1 && pagesizes[1] == 0,
 		    ("pmap_init: can't assign to pagesizes[1]"));
 		pagesizes[1] = NBPDR;
+		if ((amd_feature & AMDID_PAGE1GB) != 0) {
+			KASSERT(MAXPAGESIZES > 1 && pagesizes[2] == 0,
+			    ("pmap_init: can't assign to pagesizes[2]"));
+			pagesizes[2] = NBPDP;
+		}
 	}
 
 	/*