--- a/sys/dev/drm/radeon/r100.c
+++ b/sys/dev/drm/radeon/r100.c
@@ -2323,7 +2323,7 @@
 	switch (prim_walk) {
 	case 1:
 		for (i = 0; i < track->num_arrays; i++) {
-			size = track->arrays[i].esize * track->max_indx * 4;
+			size = (u64)track->arrays[i].esize * track->max_indx * 4;
 			if (track->arrays[i].robj == NULL) {
 				DRM_ERROR("(PW %u) Vertex array %u no buffer "
 					  "bound\n", prim_walk, i);
@@ -2342,7 +2342,7 @@
 		break;
 	case 2:
 		for (i = 0; i < track->num_arrays; i++) {
-			size = track->arrays[i].esize * (nverts - 1) * 4;
+			size = (u64)track->arrays[i].esize * (nverts - 1) * 4;
 			if (track->arrays[i].robj == NULL) {
 				DRM_ERROR("(PW %u) Vertex array %u no buffer "
 					  "bound\n", prim_walk, i);