diff --git a/Google.Protobuf/Reflection/FieldCollection.vb b/Google.Protobuf/Reflection/FieldCollection.vb
new file mode 100644
index 0000000..7d8852d
--- /dev/null
+++ b/Google.Protobuf/Reflection/FieldCollection.vb
@@ -0,0 +1,81 @@
+Namespace Google.Protobuf.Reflection
+
+    ''' <summary>
+    ''' A collection to simplify retrieving the field accessor for a particular field.
+    ''' </summary>
+    Public NotInheritable Class FieldCollection
+        Private ReadOnly messageDescriptor As MessageDescriptor
+
+        Friend Sub New(messageDescriptor As MessageDescriptor)
+            Me.messageDescriptor = messageDescriptor
+        End Sub
+
+        ''' <value>
+        ''' Returns the fields in the message as an immutable list, in the order in which they
+        ''' are declared in the source .proto file.
+        ''' </value>
+        Public Function InDeclarationOrder() As IList(Of FieldDescriptor)
+            Return messageDescriptor.fieldsInDeclarationOrder
+        End Function
+
+        ''' <value>
+        ''' Returns the fields in the message as an immutable list, in ascending field number
+        ''' order. Field numbers need not be contiguous, so there is no direct mapping from the
+        ''' index in the list to the field number; to retrieve a field by field number, it is better
+        ''' to use the <see cref="FieldCollection"/> indexer.
+        ''' </value>
+        Public Function InFieldNumberOrder() As IList(Of FieldDescriptor)
+            Return messageDescriptor.fieldsInNumberOrder
+        End Function
+
+        ' TODO: consider making this public in the future. (Being conservative for now...)
+
+        ''' <value>
+        ''' Returns a read-only dictionary mapping the field names in this message as they're available
+        ''' in the JSON representation to the field descriptors. For example, a field <c>foo_bar</c>
+        ''' in the message would result two entries, one with a key <c>fooBar</c> and one with a key
+        ''' <c>foo_bar</c>, both referring to the same field.
+        ''' </value>
+        Friend Function ByJsonName() As IDictionary(Of String, FieldDescriptor)
+            Return messageDescriptor.jsonFieldMap
+        End Function
+
+        ''' <summary>
+        ''' Retrieves the descriptor for the field with the given number.
+        ''' </summary>
+        ''' <param name="number">Number of the field to retrieve the descriptor for</param>
+        ''' <returns>The accessor for the given field</returns>
+        ''' <exception cref="KeyNotFoundException">The message descriptor does not contain a field
+        ''' with the given number</exception>
+        Default Public ReadOnly Property Item(number As Integer) As FieldDescriptor
+            Get
+                Dim fieldDescriptor = messageDescriptor.FindFieldByNumber(number)
+
+                If fieldDescriptor Is Nothing Then
+                    Throw New KeyNotFoundException("No such field number")
+                End If
+
+                Return fieldDescriptor
+            End Get
+        End Property
+
+        ''' <summary>
+        ''' Retrieves the descriptor for the field with the given name.
+        ''' </summary>
+        ''' <param name="name">Name of the field to retrieve the descriptor for</param>
+        ''' <returns>The descriptor for the given field</returns>
+        ''' <exception cref="KeyNotFoundException">The message descriptor does not contain a field
+        ''' with the given name</exception>
+        Default Public ReadOnly Property Item(name As String) As FieldDescriptor
+            Get
+                Dim fieldDescriptor = messageDescriptor.FindFieldByName(name)
+
+                If fieldDescriptor Is Nothing Then
+                    Throw New KeyNotFoundException("No such field name")
+                End If
+
+                Return fieldDescriptor
+            End Get
+        End Property
+    End Class
+End Namespace
\ No newline at end of file
diff --git a/Google.Protobuf/Reflection/MessageDescriptor.vb b/Google.Protobuf/Reflection/MessageDescriptor.vb
index dc00551..128c1cd 100644
--- a/Google.Protobuf/Reflection/MessageDescriptor.vb
+++ b/Google.Protobuf/Reflection/MessageDescriptor.vb
@@ -58,9 +58,9 @@ Namespace Google.Protobuf.Reflection
             "google/protobuf/struct.proto",
             "google/protobuf/type.proto"
         }
-        Private ReadOnly fieldsInDeclarationOrder As IList(Of FieldDescriptor)
-        Private ReadOnly fieldsInNumberOrder As IList(Of FieldDescriptor)
-        Private ReadOnly jsonFieldMap As IDictionary(Of String, FieldDescriptor)
+        Friend ReadOnly fieldsInDeclarationOrder As IList(Of FieldDescriptor)
+        Friend ReadOnly fieldsInNumberOrder As IList(Of FieldDescriptor)
+        Friend ReadOnly jsonFieldMap As IDictionary(Of String, FieldDescriptor)
 
         Friend Sub New(proto As DescriptorProto, file As FileDescriptor, parent As MessageDescriptor, typeIndex As Integer, generatedCodeInfo As GeneratedClrTypeInfo)
             MyBase.New(file, file.ComputeFullName(parent, proto.Name), typeIndex)
@@ -235,84 +235,5 @@ Namespace Google.Protobuf.Reflection
                 oneof.CrossLink()
             Next
         End Sub
-
-        ''' <summary>
-        ''' A collection to simplify retrieving the field accessor for a particular field.
-        ''' </summary>
-        Public NotInheritable Class FieldCollection
-            Private ReadOnly messageDescriptor As MessageDescriptor
-
-            Friend Sub New(messageDescriptor As MessageDescriptor)
-                Me.messageDescriptor = messageDescriptor
-            End Sub
-
-            ''' <value>
-            ''' Returns the fields in the message as an immutable list, in the order in which they
-            ''' are declared in the source .proto file.
-            ''' </value>
-            Public Function InDeclarationOrder() As IList(Of FieldDescriptor)
-                Return messageDescriptor.fieldsInDeclarationOrder
-            End Function
-
-            ''' <value>
-            ''' Returns the fields in the message as an immutable list, in ascending field number
-            ''' order. Field numbers need not be contiguous, so there is no direct mapping from the
-            ''' index in the list to the field number; to retrieve a field by field number, it is better
-            ''' to use the <see cref="FieldCollection"/> indexer.
-            ''' </value>
-            Public Function InFieldNumberOrder() As IList(Of FieldDescriptor)
-                Return messageDescriptor.fieldsInNumberOrder
-            End Function
-
-            ' TODO: consider making this public in the future. (Being conservative for now...)
-
-            ''' <value>
-            ''' Returns a read-only dictionary mapping the field names in this message as they're available
-            ''' in the JSON representation to the field descriptors. For example, a field <c>foo_bar</c>
-            ''' in the message would result two entries, one with a key <c>fooBar</c> and one with a key
-            ''' <c>foo_bar</c>, both referring to the same field.
-            ''' </value>
-            Friend Function ByJsonName() As IDictionary(Of String, FieldDescriptor)
-                Return messageDescriptor.jsonFieldMap
-            End Function
-
-            ''' <summary>
-            ''' Retrieves the descriptor for the field with the given number.
-            ''' </summary>
-            ''' <param name="number">Number of the field to retrieve the descriptor for</param>
-            ''' <returns>The accessor for the given field</returns>
-            ''' <exception cref="KeyNotFoundException">The message descriptor does not contain a field
-            ''' with the given number</exception>
-            Default Public ReadOnly Property Item(number As Integer) As FieldDescriptor
-                Get
-                    Dim fieldDescriptor = messageDescriptor.FindFieldByNumber(number)
-
-                    If fieldDescriptor Is Nothing Then
-                        Throw New KeyNotFoundException("No such field number")
-                    End If
-
-                    Return fieldDescriptor
-                End Get
-            End Property
-
-            ''' <summary>
-            ''' Retrieves the descriptor for the field with the given name.
-            ''' </summary>
-            ''' <param name="name">Name of the field to retrieve the descriptor for</param>
-            ''' <returns>The descriptor for the given field</returns>
-            ''' <exception cref="KeyNotFoundException">The message descriptor does not contain a field
-            ''' with the given name</exception>
-            Default Public ReadOnly Property Item(name As String) As FieldDescriptor
-                Get
-                    Dim fieldDescriptor = messageDescriptor.FindFieldByName(name)
-
-                    If fieldDescriptor Is Nothing Then
-                        Throw New KeyNotFoundException("No such field name")
-                    End If
-
-                    Return fieldDescriptor
-                End Get
-            End Property
-        End Class
     End Class
 End Namespace