diff --git a/Src/CommandLine/CommandInterface.cs b/Src/CommandLine/CommandInterface.cs
old mode 100644
new mode 100755
index c375509..01f7d11
--- a/Src/CommandLine/CommandInterface.cs
+++ b/Src/CommandLine/CommandInterface.cs
@@ -2138,7 +2138,14 @@ private void DoInteractiveHelp(string s)
 
         private void DoFetchConstraints(string s) 
         {
+            var cmdParts = s.Split(cmdSplitChars, 3, StringSplitOptions.RemoveEmptyEntries);
+            if (cmdParts.Length < 2 || cmdParts.Length > 5)
+            {
+                sink.WriteMessageLine(FetchConstraintsMsg, SeverityKind.Warning);
+                return;
+            }
 
+            sink.WriteMessageLine("Fetching constraints...");
         } 
 
         private void DoConfigHelp(string s)