diff --git a/src/game/vmap/WorldModel.cpp b/src/game/vmap/WorldModel.cpp
index fe52ccfd9..831a4e3be 100644
--- a/src/game/vmap/WorldModel.cpp
+++ b/src/game/vmap/WorldModel.cpp
@@ -150,10 +150,12 @@ namespace VMAP
     {
         float tx_f = (pos.x - iCorner.x)/LIQUID_TILE_SIZE;
         uint32 tx = uint32(tx_f);
-        if (tx >= iTilesX) return false;
+        if (tx_f < 0.0f || tx >= iTilesX)
+            return false;
         float ty_f = (pos.y - iCorner.y)/LIQUID_TILE_SIZE;
         uint32 ty = uint32(ty_f);
-        if (ty >= iTilesY) return false;
+        if (ty_f < 0.0f || ty >= iTilesY)
+            return false;
 
         // check if tile shall be used for liquid level
         // checking for 0x08 *might* be enough, but disabled tiles always are 0x?F:
diff --git a/src/shared/revision_nr.h b/src/shared/revision_nr.h
index 184a3e2e0..f0dac9905 100644
--- a/src/shared/revision_nr.h
+++ b/src/shared/revision_nr.h
@@ -1,4 +1,4 @@
 #ifndef __REVISION_NR_H__
 #define __REVISION_NR_H__
- #define REVISION_NR "11305"
+ #define REVISION_NR "11306"
 #endif // __REVISION_NR_H__