diff --git a/asm/field_map_obj.s b/asm/field_map_obj.s
index 27e1363508..2eac13c307 100644
--- a/asm/field_map_obj.s
+++ b/asm/field_map_obj.s
@@ -5,50 +5,6 @@
 
 	.text
 
-	thumb_func_start sub_808E78C
-sub_808E78C: @ 808E78C
-	push {r4,lr}
-	sub sp, 0x4
-	lsls r0, 24
-	lsrs r0, 24
-	lsls r1, 24
-	lsrs r1, 24
-	lsls r2, 24
-	lsrs r2, 24
-	lsls r3, 24
-	lsrs r4, r3, 24
-	mov r3, sp
-	bl TryGetFieldObjectIdByLocalIdAndMap
-	lsls r0, 24
-	cmp r0, 0
-	bne _0808E7D2
-	mov r0, sp
-	ldrb r0, [r0]
-	lsls r2, r0, 3
-	adds r2, r0
-	lsls r2, 2
-	ldr r0, =gMapObjects
-	adds r2, r0
-	ldrb r1, [r2, 0x4]
-	lsls r0, r1, 4
-	adds r0, r1
-	lsls r0, 2
-	ldr r1, =gSprites
-	adds r0, r1
-	ldrb r1, [r2, 0x3]
-	movs r3, 0x4
-	orrs r1, r3
-	strb r1, [r2, 0x3]
-	adds r0, 0x43
-	strb r4, [r0]
-_0808E7D2:
-	add sp, 0x4
-	pop {r4}
-	pop {r0}
-	bx r0
-	.pool
-	thumb_func_end sub_808E78C
-
 	thumb_func_start sub_808E7E4
 sub_808E7E4: @ 808E7E4
 	push {lr}
diff --git a/src/field_map_obj.c b/src/field_map_obj.c
index ac4f85a47c..a4d7e40974 100644
--- a/src/field_map_obj.c
+++ b/src/field_map_obj.c
@@ -1064,3 +1064,18 @@ void sub_808E75C(s16 x, s16 y)
         mapObject->mapobj_bit_2 = TRUE;
     }
 }
+
+void sub_808E78C(u8 localId, u8 mapNum, u8 mapGroup, u8 subpriority)
+{
+    u8 mapObjectId;
+    struct MapObject *mapObject;
+    struct Sprite *sprite;
+
+    if (!TryGetFieldObjectIdByLocalIdAndMap(localId, mapNum, mapGroup, &mapObjectId))
+    {
+        mapObject = &gMapObjects[mapObjectId];
+        sprite = &gSprites[mapObject->spriteId];
+        mapObject->mapobj_bit_26 = TRUE;
+        sprite->subpriority = subpriority;
+    }
+}