diff --git a/src/code/z_bgcheck.c b/src/code/z_bgcheck.c
index 8bcf727f9b..8050a14112 100644
--- a/src/code/z_bgcheck.c
+++ b/src/code/z_bgcheck.c
@@ -4239,7 +4239,7 @@ s32 WaterBox_GetSurface1(PlayState* play, CollisionContext* colCtx, f32 x, f32 z
 s32 WaterBox_GetSurfaceImpl(PlayState* play, CollisionContext* colCtx, f32 x, f32 z, f32* ySurface,
                             WaterBox** outWaterBox) {
     CollisionHeader* colHeader = colCtx->colHeader;
-    u32 room;
+    s32 room;
     WaterBox* curWaterBox;
 
     if (colHeader->numWaterBoxes == 0 || colHeader->waterBoxes == SEGMENTED_TO_VIRTUAL(NULL)) {
@@ -4346,7 +4346,7 @@ u32 WaterBox_GetLightIndex(CollisionContext* colCtx, WaterBox* waterBox) {
  */
 s32 func_800425B0(PlayState* play, CollisionContext* colCtx, f32 x, f32 z, f32* ySurface, WaterBox** outWaterBox) {
     CollisionHeader* colHeader = colCtx->colHeader;
-    u32 room;
+    s32 room;
     WaterBox* curWaterBox;
 
     if (colHeader->numWaterBoxes == 0 || colHeader->waterBoxes == SEGMENTED_TO_VIRTUAL(NULL)) {