diff --git a/src/battle.c b/src/battle.c
index 44299df1e..599631e30 100644
--- a/src/battle.c
+++ b/src/battle.c
@@ -1927,7 +1927,7 @@ int skilldiff(troop at, troop dt, int dist)
         }
         if (b->type->flags & BTF_FORTIFICATION) {
             int stage = buildingeffsize(b, false);
-            int beff = building_protection(b->type, stage);
+            int beff = bt_protection(b->type, stage);
             if (beff > 0) {
                 skdiff -= beff;
                 is_protected = 2;
diff --git a/src/battle.test.c b/src/battle.test.c
index 08adce803..41ae94db6 100644
--- a/src/battle.test.c
+++ b/src/battle.test.c
@@ -325,19 +325,19 @@ static void test_building_defense_bonus(CuTest * tc)
     btype = setup_castle();
 
     btype->maxsize = -1; /* unlimited buildigs get the castle bonus */
-    CuAssertIntEquals(tc, 0, building_protection(btype, 0));
-    CuAssertIntEquals(tc, 1, building_protection(btype, 1));
-    CuAssertIntEquals(tc, 3, building_protection(btype, 2));
-    CuAssertIntEquals(tc, 5, building_protection(btype, 3));
-    CuAssertIntEquals(tc, 8, building_protection(btype, 4));
-    CuAssertIntEquals(tc, 12, building_protection(btype, 5));
-    CuAssertIntEquals(tc, 12, building_protection(btype, 6));
+    CuAssertIntEquals(tc, 0, bt_protection(btype, 0));
+    CuAssertIntEquals(tc, 1, bt_protection(btype, 1));
+    CuAssertIntEquals(tc, 3, bt_protection(btype, 2));
+    CuAssertIntEquals(tc, 5, bt_protection(btype, 3));
+    CuAssertIntEquals(tc, 8, bt_protection(btype, 4));
+    CuAssertIntEquals(tc, 12, bt_protection(btype, 5));
+    CuAssertIntEquals(tc, 12, bt_protection(btype, 6));
 
     btype->maxsize = 10; /* limited-size buildings are treated like an E3 watchtower */
-    CuAssertIntEquals(tc, 0, building_protection(btype, 0));
-    CuAssertIntEquals(tc, 1, building_protection(btype, 1));
-    CuAssertIntEquals(tc, 2, building_protection(btype, 2));
-    CuAssertIntEquals(tc, 2, building_protection(btype, 3));
+    CuAssertIntEquals(tc, 0, bt_protection(btype, 0));
+    CuAssertIntEquals(tc, 1, bt_protection(btype, 1));
+    CuAssertIntEquals(tc, 2, bt_protection(btype, 2));
+    CuAssertIntEquals(tc, 2, bt_protection(btype, 3));
     test_teardown();
 }
 
diff --git a/src/kernel/building.c b/src/kernel/building.c
index d0a41c661..7dd4a523f 100644
--- a/src/kernel/building.c
+++ b/src/kernel/building.c
@@ -320,7 +320,7 @@ int cmp_castle_size(const building * b, const building * a)
 static const int castle_bonus[6] = { 0, 1, 3, 5, 8, 12 };
 static const int watch_bonus[3] = { 0, 1, 2 };
 
-int building_protection(const building_type * btype, int stage)
+int bt_protection(const building_type * btype, int stage)
 {
     assert(btype->flags & BTF_FORTIFICATION);
     if (btype->maxsize < 0) {
diff --git a/src/kernel/building.h b/src/kernel/building.h
index dfe1b544a..7b48aa3ad 100644
--- a/src/kernel/building.h
+++ b/src/kernel/building.h
@@ -68,7 +68,7 @@ extern "C" {
     extern struct attrib_type at_building_generic_type;
 
     int cmp_castle_size(const struct building *b, const struct building *a);
-    int building_protection(const struct building_type *btype, int stage);
+    int bt_protection(const struct building_type *btype, int stage);
     building_type *bt_get_or_create(const char *name);
     bool bt_changed(int *cache);
     const building_type *bt_find(const char *name);