diff --git a/src/viewport.cpp b/src/viewport.cpp
--- a/src/viewport.cpp
+++ b/src/viewport.cpp
@@ -599,7 +599,7 @@ void OffsetGroundSprite(int x, int y)
 	}
 
 	/* _vd.last_child == NULL if foundation sprite was clipped by the viewport bounds */
-	if (_vd.last_child != NULL) _vd.foundation[_vd.foundation_part] = _vd.parent_sprites_to_draw.size() - 1;
+	if (_vd.last_child != NULL) _vd.foundation[_vd.foundation_part] = (uint)_vd.parent_sprites_to_draw.size() - 1;
 
 	_vd.foundation_offset[_vd.foundation_part].x = x * ZOOM_LVL_BASE;
 	_vd.foundation_offset[_vd.foundation_part].y = y * ZOOM_LVL_BASE;
@@ -826,7 +826,7 @@ void AddChildSpriteScreen(SpriteID image
 		pal = PALETTE_TO_TRANSPARENT;
 	}
 
-	*_vd.last_child = _vd.child_screen_sprites_to_draw.size();
+	*_vd.last_child = (uint)_vd.child_screen_sprites_to_draw.size();
 
 	/*C++17: ChildScreenSpriteToDraw &cs = */ _vd.child_screen_sprites_to_draw.emplace_back();
 	ChildScreenSpriteToDraw &cs = _vd.child_screen_sprites_to_draw.back();