diff --git a/src/main/resources/assets/computercraft/lua/rom/programs/copy.lua b/src/main/resources/assets/computercraft/lua/rom/programs/copy.lua
index 344903f6d..8158b84a5 100644
--- a/src/main/resources/assets/computercraft/lua/rom/programs/copy.lua
+++ b/src/main/resources/assets/computercraft/lua/rom/programs/copy.lua
@@ -13,7 +13,11 @@ if #tFiles > 0 then
         if fs.isDir( sDest ) then
             fs.copy( sFile, fs.combine( sDest, fs.getName(sFile) ) )
         elseif #tFiles == 1 then
-            fs.copy( sFile, sDest )
+            if fs.exists( sDest ) then
+                 printError( "Destination exists" )
+            else
+                 fs.copy( sFile, sDest )
+            end
         else
             printError( "Cannot overwrite file multiple times" )
             return
diff --git a/src/main/resources/assets/computercraft/lua/rom/programs/mkdir.lua b/src/main/resources/assets/computercraft/lua/rom/programs/mkdir.lua
index 956123ff6..98585d3f1 100644
--- a/src/main/resources/assets/computercraft/lua/rom/programs/mkdir.lua
+++ b/src/main/resources/assets/computercraft/lua/rom/programs/mkdir.lua
@@ -5,5 +5,11 @@ if #tArgs < 1 then
 end
 
 local sNewDir = shell.resolve( tArgs[1] )
+
+if fs.exists( sNewDir ) and not fs.isDir(sNewDir) then
+    printError( "Destination exists" )
+    return
+end
+
 fs.makeDir( sNewDir )
 
diff --git a/src/main/resources/assets/computercraft/lua/rom/programs/rename.lua b/src/main/resources/assets/computercraft/lua/rom/programs/rename.lua
index 6054feb04..f22561c26 100644
--- a/src/main/resources/assets/computercraft/lua/rom/programs/rename.lua
+++ b/src/main/resources/assets/computercraft/lua/rom/programs/rename.lua
@@ -6,4 +6,9 @@ end
 
 local sSource = shell.resolve( tArgs[1] )
 local sDest = shell.resolve( tArgs[2] )
+
+if fs.exists( sDest ) then
+    printError( "Destination exists" )
+end
+
 fs.move( sSource, sDest )