diff --git a/Source/cmListCommand.cxx b/Source/cmListCommand.cxx
index 9d4f17529..7848424c6 100644
--- a/Source/cmListCommand.cxx
+++ b/Source/cmListCommand.cxx
@@ -429,6 +429,12 @@ bool cmListCommand
     this->SetError("sub-command REVERSE requires a list as an argument.");
     return false;
     }
+  else if(args.size() > 2)
+    {
+    this->SetError(
+      "sub-command REVERSE only takes one argument.");
+    return false;
+    }
 
   const std::string& listName = args[1];
   // expand the variable
@@ -463,6 +469,12 @@ bool cmListCommand
       "sub-command REMOVE_DUPLICATES requires a list as an argument.");
     return false;
     }
+  else if(args.size() > 2)
+    {
+    this->SetError(
+      "sub-command REMOVE_DUPLICATES only takes one argument.");
+    return false;
+    }
 
   const std::string& listName = args[1];
   // expand the variable
@@ -506,6 +518,12 @@ bool cmListCommand
     this->SetError("sub-command SORT requires a list as an argument.");
     return false;
     }
+  else if(args.size() > 2)
+    {
+    this->SetError(
+      "sub-command SORT only takes one argument.");
+    return false;
+    }
 
   const std::string& listName = args[1];
   // expand the variable