diff --git a/src/lib/subs/lndsub.c b/src/lib/subs/lndsub.c
index b3483b79..30630a70 100644
--- a/src/lib/subs/lndsub.c
+++ b/src/lib/subs/lndsub.c
@@ -412,7 +412,7 @@ lnd_sel(struct nstr_item *ni, struct emp_qelem *list)
 	 * but much of the code assumes that only the land unit's
 	 * owner can march it.
 	 */
-	if (land.lnd_own != player->cnum)
+	if (!land.lnd_own || land.lnd_own != player->cnum)
 	    continue;
 	if (opt_MARKET) {
 	    if (ontradingblock(EF_LAND, &land)) {
diff --git a/src/lib/subs/plnsub.c b/src/lib/subs/plnsub.c
index c0e0816e..a167f636 100644
--- a/src/lib/subs/plnsub.c
+++ b/src/lib/subs/plnsub.c
@@ -538,7 +538,7 @@ pln_sel(struct nstr_item *ni, struct emp_qelem *list, struct sctstr *ap,
 	 * much of the code assumes that only the plane's owner can
 	 * fly it.
 	 */
-	if (plane.pln_own != player->cnum)
+	if (!plane.pln_own || plane.pln_own != player->cnum)
 	    continue;
 	if (plane.pln_mobil <= 0)
 	    continue;
diff --git a/src/lib/subs/shpsub.c b/src/lib/subs/shpsub.c
index 05d2112d..3a45c725 100644
--- a/src/lib/subs/shpsub.c
+++ b/src/lib/subs/shpsub.c
@@ -70,7 +70,7 @@ shp_sel(struct nstr_item *ni, struct emp_qelem *list)
 	 * much of the code assumes that only the ship's owner can
 	 * navigate it.
 	 */
-	if (ship.shp_own != player->cnum)
+	if (!ship.shp_own || ship.shp_own != player->cnum)
 	    continue;
 	mcp = &mchr[(int)ship.shp_type];
 	if (opt_MARKET) {