diff --git a/src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb b/src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb
index 08f8394987164..f210191c622de 100644
--- a/src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb
+++ b/src/Compilers/VisualBasic/Portable/Symbols/AssemblySymbol.vb
@@ -764,7 +764,7 @@ Namespace Microsoft.CodeAnalysis.VisualBasic.Symbols
 
         Private ReadOnly Property IAssemblySymbol_Modules As IEnumerable(Of IModuleSymbol) Implements IAssemblySymbol.Modules
             Get
-                Return Me.Modules
+                Return ImmutableArray(Of IModuleSymbol).CastUp(Me.Modules)
             End Get
         End Property
 
diff --git a/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/SymbolKey/SymbolKey.ModuleSymbolKey.cs b/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/SymbolKey/SymbolKey.ModuleSymbolKey.cs
index 4b0d33cb64367..259382c0c495c 100644
--- a/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/SymbolKey/SymbolKey.ModuleSymbolKey.cs
+++ b/src/Workspaces/SharedUtilitiesAndExtensions/Compiler/Core/SymbolKey/SymbolKey.ModuleSymbolKey.cs
@@ -43,8 +43,7 @@ protected sealed override SymbolKeyResolution Resolve(
                 }
                 else
                 {
-                    // Visual Basic implementation of IAssemblySymbol.Modules relies on covariance of IEnumerable<T>, so
-                    // the preceding concrete type check will fail.
+                    // Otherwise fall back to generic enumeration
                     result.AddValuesIfNotNull(assemblyModules);
                 }
             }