diff --git a/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorFactory.cs b/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorFactory.cs
index 560c723a4a..0beb8d9955 100644
--- a/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorFactory.cs
+++ b/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorFactory.cs
@@ -31,14 +31,14 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
         /// <summary>
         /// Creates a <see cref="TagHelperDescriptor"/> from the given <paramref name="type"/>.
         /// </summary>
+        /// <param name="assemblyName">The assembly name that contains <paramref name="type"/>.</param>
         /// <param name="type">The type to create a <see cref="TagHelperDescriptor"/> from.</param>
         /// <returns>A <see cref="TagHelperDescriptor"/> that describes the given <paramref name="type"/>.</returns>
-        public static IEnumerable<TagHelperDescriptor> CreateDescriptors(Type type)
+        public static IEnumerable<TagHelperDescriptor> CreateDescriptors(string assemblyName, Type type)
         {
             var tagNames = GetTagNames(type);
             var typeName = type.FullName;
             var attributeDescriptors = GetAttributeDescriptors(type);
-            var assemblyName = type.GetTypeInfo().Assembly.GetName().Name;
 
             return tagNames.Select(tagName =>
                 new TagHelperDescriptor(tagName,
diff --git a/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorResolver.cs b/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorResolver.cs
index 8ddacf76cc..b053673d4a 100644
--- a/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorResolver.cs
+++ b/src/Microsoft.AspNet.Razor.Runtime/TagHelpers/TagHelperDescriptorResolver.cs
@@ -26,18 +26,23 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
 
         private readonly TagHelperTypeResolver _typeResolver;
 
-        // internal for testing
-        internal TagHelperDescriptorResolver(TagHelperTypeResolver typeResolver)
-        {
-            _typeResolver = typeResolver;
-        }
-
         /// <summary>
         /// Instantiates a new instance of the <see cref="TagHelperDescriptorResolver"/> class.
         /// </summary>
         public TagHelperDescriptorResolver()
             : this(new TagHelperTypeResolver())
         {
+
+        }
+
+        /// <summary>
+        /// Instantiates a new instance of <see cref="TagHelperDescriptorResolver"/> class with the
+        /// specified <paramref name="typeResolver"/>.
+        /// </summary>
+        /// <param name="typeResolver">The <see cref="TagHelperTypeResolver"/>.</param>
+        public TagHelperDescriptorResolver(TagHelperTypeResolver typeResolver)
+        {
+            _typeResolver = typeResolver;
         }
 
         /// <inheritdoc />
@@ -112,7 +117,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             var tagHelperTypes = _typeResolver.Resolve(assemblyName, documentLocation, errorSink);
 
             // Convert types to TagHelperDescriptors
-            var descriptors = tagHelperTypes.SelectMany(TagHelperDescriptorFactory.CreateDescriptors);
+            var descriptors = tagHelperTypes.SelectMany(
+                type => TagHelperDescriptorFactory.CreateDescriptors(assemblyName, type));
 
             return descriptors;
         }
diff --git a/src/Microsoft.AspNet.Razor/RazorEngineHost.cs b/src/Microsoft.AspNet.Razor/RazorEngineHost.cs
index ba5b501398..f73336cecc 100644
--- a/src/Microsoft.AspNet.Razor/RazorEngineHost.cs
+++ b/src/Microsoft.AspNet.Razor/RazorEngineHost.cs
@@ -115,7 +115,7 @@ namespace Microsoft.AspNet.Razor
         /// <summary>
         /// The <see cref="ITagHelperDescriptorResolver"/> used to resolve <see cref="TagHelperDescriptor"/>s.
         /// </summary>
-        public virtual ITagHelperDescriptorResolver TagHelperDescriptorResolver { get; protected set; }
+        public virtual ITagHelperDescriptorResolver TagHelperDescriptorResolver { get; set; }
 
         /// <summary>
         /// Boolean indicating if instrumentation code should be injected into the output page
diff --git a/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorFactoryTest.cs b/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorFactoryTest.cs
index fa229c4bc4..4be74b02fa 100644
--- a/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorFactoryTest.cs
+++ b/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorFactoryTest.cs
@@ -40,7 +40,7 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             string expectedAttributeName)
         {
             // Arrange & Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(tagHelperType);
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName, tagHelperType);
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -69,7 +69,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(OverriddenAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(OverriddenAttributeTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -96,7 +97,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(InheritedOverriddenAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(InheritedOverriddenAttributeTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -122,7 +124,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(InheritedNotOverriddenAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(InheritedNotOverriddenAttributeTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -137,7 +140,7 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                 new TagHelperDescriptor("object", "System.Object", objectAssemblyName);
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(object));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(objectAssemblyName, typeof(object));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -159,7 +162,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                 });
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(InheritedSingleAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(InheritedSingleAttributeTagHelper));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -180,7 +184,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                 });
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(SingleAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(SingleAttributeTagHelper));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -202,7 +207,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                 });
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(MissingAccessorTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(MissingAccessorTagHelper));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -225,7 +231,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                 });
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(PrivateAccessorTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(PrivateAccessorTagHelper));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -255,7 +262,7 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(MultiTagTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName, typeof(MultiTagTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -275,7 +282,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
                     });
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(InheritedMultiTagTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(InheritedMultiTagTagHelper));
 
             // Assert
             var descriptor = Assert.Single(descriptors);
@@ -298,7 +306,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(DuplicateTagNameTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(DuplicateTagNameTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -315,7 +324,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(OverrideNameTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(OverrideNameTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
@@ -341,7 +351,8 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             };
 
             // Act
-            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(typeof(MultipleAttributeTagHelper));
+            var descriptors = TagHelperDescriptorFactory.CreateDescriptors(AssemblyName,
+                typeof(MultipleAttributeTagHelper));
 
             // Assert
             Assert.Equal(expectedDescriptors, descriptors, CompleteTagHelperDescriptorComparer.Default);
diff --git a/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorResolverTest.cs b/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorResolverTest.cs
index 92c5c33e0d..343ff89ddb 100644
--- a/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorResolverTest.cs
+++ b/test/Microsoft.AspNet.Razor.Runtime.Test/TagHelpers/TagHelperDescriptorResolverTest.cs
@@ -689,24 +689,38 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             Assert.Empty(descriptors);
         }
 
+        public static TheoryData<string> DescriptorResolver_IgnoresSpacesData
+        {
+            get
+            {
+                var typeName = typeof(Valid_PlainTagHelper).FullName;
+                return new TheoryData<string>
+                {
+                    $"{typeName},{AssemblyName}",
+                    $"    {typeName},{AssemblyName}",
+                    $"{typeName}    ,{AssemblyName}",
+                    $"    {typeName}    ,{AssemblyName}",
+                    $"{typeName},    {AssemblyName}",
+                    $"{typeName},{AssemblyName}    ",
+                    $"{typeName},    {AssemblyName}    ",
+                    $"    {typeName},    {AssemblyName}    ",
+                    $"    {typeName}    ,    {AssemblyName}    "
+                };
+            }
+        }
+
         [Theory]
-        [InlineData("Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,MyAssembly")]
-        [InlineData("    Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,MyAssembly")]
-        [InlineData("Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper    ,MyAssembly")]
-        [InlineData("    Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper    ,MyAssembly")]
-        [InlineData("Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,    MyAssembly")]
-        [InlineData("Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,MyAssembly    ")]
-        [InlineData("Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,    MyAssembly    ")]
-        [InlineData("    Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper,    MyAssembly    ")]
-        [InlineData("    Microsoft.AspNet.Razor.Runtime.TagHelpers.Valid_PlainTagHelper    ,    MyAssembly    ")]
+        [MemberData(nameof(DescriptorResolver_IgnoresSpacesData))]
         public void DescriptorResolver_IgnoresSpaces(string lookupText)
         {
             // Arrange
+            var invoked = false;
             var tagHelperTypeResolver = new TestTagHelperTypeResolver(TestableTagHelpers)
             {
                 OnGetExportedTypes = (assemblyName) =>
                 {
-                    Assert.Equal("MyAssembly", assemblyName.Name);
+                    Assert.Equal(AssemblyName, assemblyName.Name);
+                    invoked = true;
                 }
             };
             var tagHelperDescriptorResolver = new TestTagHelperDescriptorResolver(tagHelperTypeResolver);
@@ -715,7 +729,10 @@ namespace Microsoft.AspNet.Razor.Runtime.TagHelpers
             var descriptors = tagHelperDescriptorResolver.Resolve(lookupText);
 
             // Assert
-            Assert.Empty(descriptors);
+            Assert.True(invoked);
+            var descriptor = Assert.Single(descriptors);
+            Assert.Equal(AssemblyName, descriptor.AssemblyName);
+            Assert.Equal(typeof(Valid_PlainTagHelper).FullName, descriptor.TypeName);
         }
 
         [Fact]