diff --git a/src/dotnet/CommandLine/CommandLineApplication.cs b/src/dotnet/CommandLine/CommandLineApplication.cs
index f440a5595..fc859dd14 100644
--- a/src/dotnet/CommandLine/CommandLineApplication.cs
+++ b/src/dotnet/CommandLine/CommandLineApplication.cs
@@ -56,28 +56,33 @@ namespace Microsoft.DotNet.Cli.CommandLine
         public bool HandleRemainingArguments { get; set; }
         public string ArgumentSeparatorHelpText { get; set; }
 
-        public CommandLineApplication Command(string name, bool throwOnUnexpectedArg = true)
+        public CommandLineApplication AddCommand(string name, bool throwOnUnexpectedArg = true)
         {
-            return Command(name, _ => { }, throwOnUnexpectedArg);
+            return AddCommand(name, _ => { }, throwOnUnexpectedArg);
         }
 
-        public CommandLineApplication Command(string name, Action<CommandLineApplication> configuration,
+        public CommandLineApplication AddCommand(string name, Action<CommandLineApplication> configuration,
             bool throwOnUnexpectedArg = true)
         {
             var command = new CommandLineApplication(throwOnUnexpectedArg) { Name = name };
-            return Command(command, configuration, throwOnUnexpectedArg);
+            return AddCommand(command, configuration, throwOnUnexpectedArg);
         }
 
-        public CommandLineApplication Command(CommandLineApplication command, bool throwOnUnexpectedArg = true)
+        public CommandLineApplication AddCommand(CommandLineApplication command, bool throwOnUnexpectedArg = true)
         {
-            return Command(command, _ => { }, throwOnUnexpectedArg);
+            return AddCommand(command, _ => { }, throwOnUnexpectedArg);
         }
 
-        public CommandLineApplication Command(
+        public CommandLineApplication AddCommand(
             CommandLineApplication command,
             Action<CommandLineApplication> configuration,
             bool throwOnUnexpectedArg = true)
         {
+            if (command == null || configuration == null)
+            {
+                throw new NullReferenceException();
+            }
+
             command.Parent = this;
             Commands.Add(command);
             configuration(command);
diff --git a/src/dotnet/DotNetTopLevelCommandBase.cs b/src/dotnet/DotNetTopLevelCommandBase.cs
index 4e0483503..8f547b86f 100644
--- a/src/dotnet/DotNetTopLevelCommandBase.cs
+++ b/src/dotnet/DotNetTopLevelCommandBase.cs
@@ -37,7 +37,7 @@ namespace Microsoft.DotNet.Cli
             foreach (var subCommandCreator in SubCommands)
             {
                 var subCommand = subCommandCreator();
-                command.Command(subCommand);
+                command.AddCommand(subCommand);
 
                 subCommand.OnExecute(() => {
                     try
diff --git a/src/dotnet/commands/dotnet-add/dotnet-add-p2p/Program.cs b/src/dotnet/commands/dotnet-add/dotnet-add-p2p/Program.cs
index 6107b122d..47c031bc6 100644
--- a/src/dotnet/commands/dotnet-add/dotnet-add-p2p/Program.cs
+++ b/src/dotnet/commands/dotnet-add/dotnet-add-p2p/Program.cs
@@ -41,7 +41,7 @@ namespace Microsoft.DotNet.Tools.Add.ProjectToProjectReference
 
         public override int Run(string fileOrDirectory)
         {
-            ProjectCollection projects = new ProjectCollection();
+            var projects = new ProjectCollection();
             MsbuildProject msbuildProj = MsbuildProject.FromFileOrDirectory(projects, fileOrDirectory);
 
             if (RemainingArguments.Count == 0)
@@ -51,7 +51,9 @@ namespace Microsoft.DotNet.Tools.Add.ProjectToProjectReference
 
             string frameworkString = _frameworkOption.Value();
             PathUtility.EnsureAllPathsExist(RemainingArguments, CommonLocalizableStrings.ReferenceDoesNotExist);
-            IEnumerable<MsbuildProject> refs = RemainingArguments.Select((r) => MsbuildProject.FromFile(projects, r));
+            List<MsbuildProject> refs = RemainingArguments
+                .Select((r) => MsbuildProject.FromFile(projects, r))
+                .ToList();
 
             if (frameworkString == null)
             {
@@ -108,7 +110,7 @@ namespace Microsoft.DotNet.Tools.Add.ProjectToProjectReference
             return 0;
         }
 
-        private string GetProjectNotCompatibleWithFrameworksDisplayString(MsbuildProject project, IEnumerable<string> frameworksDisplayStrings)
+        private static string GetProjectNotCompatibleWithFrameworksDisplayString(MsbuildProject project, IEnumerable<string> frameworksDisplayStrings)
         {
             var sb = new StringBuilder();
             sb.AppendLine(string.Format(CommonLocalizableStrings.ProjectNotCompatibleWithFrameworks, project.ProjectRootElement.FullPath));