diff --git a/src/Orchard.Tests/DataUtility.cs b/src/Orchard.Tests/DataUtility.cs
index 0288fcf85..b79b92afc 100644
--- a/src/Orchard.Tests/DataUtility.cs
+++ b/src/Orchard.Tests/DataUtility.cs
@@ -49,7 +49,7 @@ namespace Orchard.Tests {
 
         public static ISessionFactory CreateSessionFactory(params Type[] types) {
             return CreateSessionFactory(
-                types.Aggregate("db", (n, t) => t.FullName + "." + n),
+                string.Join(".", types.Reverse().Select(type => type.FullName)),
                 types);
         }
 
diff --git a/src/Orchard.Web/Modules/Orchard.Widgets/Commands/WidgetCommands.cs b/src/Orchard.Web/Modules/Orchard.Widgets/Commands/WidgetCommands.cs
index 2b1c61563..7dc978de2 100644
--- a/src/Orchard.Web/Modules/Orchard.Widgets/Commands/WidgetCommands.cs
+++ b/src/Orchard.Web/Modules/Orchard.Widgets/Commands/WidgetCommands.cs
@@ -76,11 +76,11 @@ namespace Orchard.Widgets.Commands {
         [CommandHelp("widget create <type> /Title:<title> /Name:<name> /Zone:<zone> /Position:<position> /Layer:<layer> [/Identity:<identity>] [/RenderTitle:true|false] [/Owner:<owner>] [/Text:<text>] [/UseLoremIpsumText:true|false] [/MenuName:<name>]\r\n\t" + "Creates a new widget")]
         [OrchardSwitches("Title,Name,Zone,Position,Layer,Identity,Owner,Text,UseLoremIpsumText,MenuName,RenderTitle")]
         public void Create(string type) {
-            var widgetTypeNames = _widgetsService.GetWidgetTypeNames();
+            var widgetTypeNames = _widgetsService.GetWidgetTypeNames().ToList();
             if (!widgetTypeNames.Contains(type)) {
                 Context.Output.WriteLine(T("Creating widget failed : type {0} was not found. Supported widget types are: {1}.", 
                     type,
-                    widgetTypeNames.Aggregate(String.Empty, (current, widgetType) => current + " " + widgetType)));
+                    string.Join(" ", widgetTypeNames)));
                 return;
             }
 
diff --git a/src/Orchard/DisplayManagement/Implementation/DisplayHelper.cs b/src/Orchard/DisplayManagement/Implementation/DisplayHelper.cs
index efe0a99f3..af01c852e 100644
--- a/src/Orchard/DisplayManagement/Implementation/DisplayHelper.cs
+++ b/src/Orchard/DisplayManagement/Implementation/DisplayHelper.cs
@@ -53,31 +53,31 @@ namespace Orchard.DisplayManagement.Implementation {
         }
 
         public class Combined : IHtmlString {
-            private readonly IEnumerable<object> _fragments;
+            private readonly IEnumerable<IHtmlString> _fragments;
 
-            public Combined(IEnumerable<object> fragments) {
+            public Combined(IEnumerable<IHtmlString> fragments) {
                 _fragments = fragments;
             }
 
             public string ToHtmlString() {
-                return _fragments.Aggregate("", (a, b) => a + b);
+                return string.Join("", _fragments);
             }
             public override string ToString() {
                 return ToHtmlString();
             }
         }
 
-        private object ShapeTypeExecute(string name, INamedEnumerable<object> parameters) {
+        private IHtmlString ShapeTypeExecute(string name, INamedEnumerable<object> parameters) {
             var shape = _shapeFactory.Create(name, parameters);
             return ShapeExecute(shape);
         }
 
-        public object ShapeExecute(Shape shape) {
+        public IHtmlString ShapeExecute(Shape shape) {
             // disambiguates the call to ShapeExecute(object) as Shape also implements IEnumerable
             return ShapeExecute((object) shape);
         }
 
-        public object ShapeExecute(object shape) {
+        public IHtmlString ShapeExecute(object shape) {
             if (shape == null) {
                 return new HtmlString(string.Empty);
             }
@@ -86,7 +86,7 @@ namespace Orchard.DisplayManagement.Implementation {
             return _displayManager.Execute(context);
         }
 
-        public IEnumerable<object> ShapeExecute(IEnumerable<object> shapes) {
+        public IEnumerable<IHtmlString> ShapeExecute(IEnumerable<object> shapes) {
             return shapes.Select(ShapeExecute).ToArray();
         }
     }
diff --git a/src/Orchard/Localization/Commands/CultureCommands.cs b/src/Orchard/Localization/Commands/CultureCommands.cs
index deb9557f6..bb0783b05 100644
--- a/src/Orchard/Localization/Commands/CultureCommands.cs
+++ b/src/Orchard/Localization/Commands/CultureCommands.cs
@@ -18,7 +18,7 @@ namespace Orchard.Localization.Commands {
         public void ListCultures() {
             Context.Output.WriteLine(T("Listing Cultures:"));
 
-            string cultures = _cultureManager.ListCultures().Aggregate<string, string>(null, (current, culture) => current + culture + " ");
+            var cultures = string.Join(" ", _cultureManager.ListCultures());
 
             Context.Output.WriteLine(cultures);
         }
diff --git a/src/Orchard/Utility/Reflect.cs b/src/Orchard/Utility/Reflect.cs
index 643a08d14..f36e0fdf9 100644
--- a/src/Orchard/Utility/Reflect.cs
+++ b/src/Orchard/Utility/Reflect.cs
@@ -105,7 +105,7 @@ namespace Orchard.Utility {
                     }
 
                     AddNames(callExpression.Object, nb);
-                    nb.Append("[" + GetArguments(callExpression.Arguments).Aggregate((a, b) => a + b) + "]");
+                    nb.Append("[" + string.Join("", GetArguments(callExpression.Arguments)) + "]");
                     break;
 
                 case ExpressionType.Parameter: