diff --git a/apps/openmw/mwworld/cellref.cpp b/apps/openmw/mwworld/cellref.cpp
index 602248bb1..70f97a612 100644
--- a/apps/openmw/mwworld/cellref.cpp
+++ b/apps/openmw/mwworld/cellref.cpp
@@ -25,7 +25,7 @@ namespace MWWorld
 
         Get the mMpNum (unique multiplayer reference number) of a CellRef
     */
-    int CellRef::getMpNum() const
+    unsigned int CellRef::getMpNum() const
     {
         return mCellRef.mMpNum;
     }
@@ -38,7 +38,7 @@ namespace MWWorld
 
         Set the mMpNum (unique multiplayer reference number) of a CellRef
     */
-    void CellRef::setMpNum(int index)
+    void CellRef::setMpNum(unsigned int index)
     {
         mCellRef.mMpNum = index;
     }
diff --git a/apps/openmw/mwworld/cellref.hpp b/apps/openmw/mwworld/cellref.hpp
index 18f8a7165..b811e3ac9 100644
--- a/apps/openmw/mwworld/cellref.hpp
+++ b/apps/openmw/mwworld/cellref.hpp
@@ -33,7 +33,7 @@ namespace MWWorld
 
             Get the mMpNum (unique multiplayer reference number) of a CellRef
         */
-        int getMpNum() const;
+        unsigned int getMpNum() const;
         /*
             End of tes3mp addition
         */
@@ -43,7 +43,7 @@ namespace MWWorld
 
             Set the mMpNum (unique multiplayer reference number) of a CellRef
         */
-        void setMpNum(int index);
+        void setMpNum(unsigned int index);
         /*
             End of tes3mp addition
         */
diff --git a/components/esm/cellref.hpp b/components/esm/cellref.hpp
index a8a90357a..36847322a 100644
--- a/components/esm/cellref.hpp
+++ b/components/esm/cellref.hpp
@@ -43,7 +43,7 @@ namespace ESM
 
                 Keep track of a multiplayer-only number unique to this object
             */
-            int mMpNum;
+            unsigned int mMpNum;
             /*
                 End of tes3mp addition
             */