diff --git a/src/kernel/building.c b/src/kernel/building.c
index 1053a7748..948797b94 100644
--- a/src/kernel/building.c
+++ b/src/kernel/building.c
@@ -98,7 +98,7 @@ bool bt_changed(int *cache)
     return false;
 }
 
-void bt_register(building_type * btype)
+static void bt_register(building_type * btype)
 {
     size_t len;
     char data[64];
diff --git a/src/kernel/building.h b/src/kernel/building.h
index edb46edfd..a2019e4a2 100644
--- a/src/kernel/building.h
+++ b/src/kernel/building.h
@@ -83,7 +83,6 @@ extern "C" {
     bool bt_changed(int *cache);
     const building_type *bt_find(const char *name);
     void free_buildingtypes(void);
-    void bt_register(struct building_type *type);
     int bt_effsize(const struct building_type *btype,
         const struct building *b, int bsize);
 
diff --git a/src/kernel/building.test.c b/src/kernel/building.test.c
index 3d25cd9a1..39b145d24 100644
--- a/src/kernel/building.test.c
+++ b/src/kernel/building.test.c
@@ -21,14 +21,13 @@ static void test_register_building(CuTest * tc)
 
     test_cleanup();
 
-    btype = (building_type *)calloc(sizeof(building_type), 1);
-    btype->_name = strdup("herp");
     CuAssertIntEquals(tc, true, bt_changed(&cache));
     CuAssertIntEquals(tc, false, bt_changed(&cache));
-    bt_register(btype);
-    CuAssertIntEquals(tc, true, bt_changed(&cache));
 
-    CuAssertPtrNotNull(tc, bt_find("herp"));
+    btype = bt_get_or_create("herp");
+    CuAssertIntEquals(tc, true, bt_changed(&cache));
+    CuAssertPtrEquals(tc, btype, (void *)bt_find("herp"));
+
     free_buildingtypes();
     CuAssertIntEquals(tc, true, bt_changed(&cache));
     test_cleanup();
diff --git a/src/kernel/ship.c b/src/kernel/ship.c
index 88c0f31e7..27db2e5c2 100644
--- a/src/kernel/ship.c
+++ b/src/kernel/ship.c
@@ -107,21 +107,25 @@ const ship_type *st_find(const char *name) {
     return st_find_i(name);
 }
 
+static void st_register(ship_type *stype) {
+    size_t len;
+    char data[64];
+
+    selist_push(&shiptypes, (void *)stype);
+
+    len = cb_new_kv(stype->_name, strlen(stype->_name), &stype, sizeof(stype), data);
+    assert(len <= sizeof(data));
+    cb_insert(&cb_shiptypes, data, len);
+}
+
 ship_type *st_get_or_create(const char * name) {
     ship_type * st = st_find_i(name);
     assert(!snames);
     if (!st) {
-        size_t len;
-        char data[64];
-
         st = (ship_type *)calloc(sizeof(ship_type), 1);
         st->_name = strdup(name);
         st->storm = 1.0;
-        selist_push(&shiptypes, (void *)st);
-
-        len = cb_new_kv(name, strlen(name), &st, sizeof(st), data);
-        assert(len <= sizeof(data));
-        cb_insert(&cb_shiptypes, data, len);
+        st_register(st);
     }
     return st;
 }
diff --git a/src/market.test.c b/src/market.test.c
index a631dbcb7..2beeaea6b 100644
--- a/src/market.test.c
+++ b/src/market.test.c
@@ -43,9 +43,7 @@ static void test_market_curse(CuTest * tc)
 
     config_set("rules.region_owners", "1");
 
-    btype = (building_type *)calloc(1, sizeof(building_type));
-    btype->_name = strdup("market");
-    bt_register(btype);
+    btype = bt_get_or_create("market");
 
     terrain = get_terrain("plain");