diff --git a/apps/openmw/mwmechanics/security.cpp b/apps/openmw/mwmechanics/security.cpp
index 5b79d821c2..e642a7bb4b 100644
--- a/apps/openmw/mwmechanics/security.cpp
+++ b/apps/openmw/mwmechanics/security.cpp
@@ -65,7 +65,7 @@ namespace MWMechanics
                 resultMessage = "#{sLockFail}";
         }
 
-        lockpick.getCellRef().setCharge(uses-1);
+        lockpick.getCellRef().setCharge(--uses);
         if (!uses)
             lockpick.getContainerStore()->remove(lockpick, 1, mActor);
     }
@@ -110,7 +110,7 @@ namespace MWMechanics
                 resultMessage = "#{sTrapFail}";
         }
 
-        probe.getCellRef().setCharge(uses-1);
+        probe.getCellRef().setCharge(--uses);
         if (!uses)
             probe.getContainerStore()->remove(probe, 1, mActor);
     }