diff --git a/src/Compilers/CSharp/Portable/Binder/LookupOptions.cs b/src/Compilers/CSharp/Portable/Binder/LookupOptions.cs
index f2ef9c1fb49fa..9c2ff89185f0d 100644
--- a/src/Compilers/CSharp/Portable/Binder/LookupOptions.cs
+++ b/src/Compilers/CSharp/Portable/Binder/LookupOptions.cs
@@ -74,11 +74,6 @@ internal enum LookupOptions
         /// </summary>
         UseBaseReferenceAccessibility = 1 << 9,
 
-        /// <summary>
-        /// Include extension members.
-        /// </summary>
-        IncludeExtensionMembers = 1 << 10,
-
         /// <summary>
         /// Consider only attribute types.
         /// </summary>
@@ -115,6 +110,8 @@ internal enum LookupOptions
         /// Consider only symbols that are user-defined operators.
         /// </summary>
         MustBeOperator = 1 << 17,
+
+        // Available 1 << 10,
     }
 
     internal static class LookupOptionExtensions
diff --git a/src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs b/src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs
index 7d96896ddd50e..5e6a5d1f8d310 100644
--- a/src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs
+++ b/src/Compilers/CSharp/Portable/Compilation/CSharpSemanticModel.cs
@@ -1419,8 +1419,7 @@ public ImmutableArray<ISymbol> LookupSymbols(
             string name = null,
             bool includeExtensions = false)
         {
-            var options = includeExtensions ? LookupOptions.IncludeExtensionMembers : LookupOptions.Default;
-            return LookupSymbolsInternal(position, container, name, options, useBaseReferenceAccessibility: false);
+            return LookupSymbolsInternal(position, container, name, LookupOptions.Default, includeExtensionMembers: includeExtensions, useBaseReferenceAccessibility: false);
         }
 
         /// <summary>
@@ -1462,7 +1461,7 @@ public ImmutableArray<ISymbol> LookupSymbols(
             int position,
             string name = null)
         {
-            return LookupSymbolsInternal(position, container: null, name: name, options: LookupOptions.Default, useBaseReferenceAccessibility: true);
+            return LookupSymbolsInternal(position, container: null, name: name, options: LookupOptions.Default, includeExtensionMembers: false, useBaseReferenceAccessibility: true);
         }
 
         /// <summary>
@@ -1488,7 +1487,7 @@ public ImmutableArray<ISymbol> LookupStaticMembers(
             NamespaceOrTypeSymbol container = null,
             string name = null)
         {
-            return LookupSymbolsInternal(position, container, name, LookupOptions.MustNotBeInstance, useBaseReferenceAccessibility: false);
+            return LookupSymbolsInternal(position, container, name, LookupOptions.MustNotBeInstance, includeExtensionMembers: false, useBaseReferenceAccessibility: false);
         }
 
         /// <summary>
@@ -1514,7 +1513,7 @@ public ImmutableArray<ISymbol> LookupNamespacesAndTypes(
             NamespaceOrTypeSymbol container = null,
             string name = null)
         {
-            return LookupSymbolsInternal(position, container, name, LookupOptions.NamespacesOrTypesOnly, useBaseReferenceAccessibility: false);
+            return LookupSymbolsInternal(position, container, name, LookupOptions.NamespacesOrTypesOnly, includeExtensionMembers: false, useBaseReferenceAccessibility: false);
         }
 
         /// <summary>
@@ -1535,7 +1534,7 @@ public ImmutableArray<ISymbol> LookupNamespacesAndTypes(
             int position,
             string name = null)
         {
-            return LookupSymbolsInternal(position, container: null, name: name, options: LookupOptions.LabelsOnly, useBaseReferenceAccessibility: false);
+            return LookupSymbolsInternal(position, container: null, name: name, options: LookupOptions.LabelsOnly, includeExtensionMembers: false, useBaseReferenceAccessibility: false);
         }
 
         /// <summary>
@@ -1563,6 +1562,7 @@ private ImmutableArray<ISymbol> LookupSymbolsInternal(
             NamespaceOrTypeSymbol container,
             string name,
             LookupOptions options,
+            bool includeExtensionMembers,
             bool useBaseReferenceAccessibility)
         {
             Debug.Assert((options & LookupOptions.UseBaseReferenceAccessibility) == 0, "Use the useBaseReferenceAccessibility parameter.");
@@ -1579,7 +1579,7 @@ private ImmutableArray<ISymbol> LookupSymbolsInternal(
 
             if ((object)container == null || container.Kind == SymbolKind.Namespace)
             {
-                options &= ~LookupOptions.IncludeExtensionMembers;
+                includeExtensionMembers = false;
             }
 
             var binder = GetEnclosingBinder(position);
@@ -1655,7 +1655,7 @@ private ImmutableArray<ISymbol> LookupSymbolsInternal(
 
             info.Free();
 
-            if ((options & LookupOptions.IncludeExtensionMembers) != 0 && container is TypeSymbol receiverType)
+            if (includeExtensionMembers && container is TypeSymbol receiverType)
             {
                 var lookupResult = LookupResult.GetInstance();
 
@@ -1753,7 +1753,7 @@ private void AppendSymbolsWithNameAndArity(
                 name,
                 arity,
                 basesBeingResolved: null,
-                options: options & ~LookupOptions.IncludeExtensionMembers,
+                options: options,
                 diagnose: false,
                 useSiteInfo: ref discardedUseSiteInfo);
 
diff --git a/src/Compilers/CSharp/Portable/Symbols/NamedTypeSymbol.cs b/src/Compilers/CSharp/Portable/Symbols/NamedTypeSymbol.cs
index c532cfd748dd0..7308c33ee858a 100644
--- a/src/Compilers/CSharp/Portable/Symbols/NamedTypeSymbol.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/NamedTypeSymbol.cs
@@ -412,7 +412,7 @@ private static bool IsValidExtensionReceiverParameter(ParameterSymbol thisParam)
         /// <remarks>Does not perform a full viability check</remarks>
         internal void GetExtensionMembers(ArrayBuilder<Symbol> members, string? name, string? alternativeName, int arity, LookupOptions options, ConsList<FieldSymbol> fieldsBeingBound)
         {
-            Debug.Assert((options & ~(LookupOptions.IncludeExtensionMembers | LookupOptions.AllMethodsOnArityZero
+            Debug.Assert((options & ~(LookupOptions.AllMethodsOnArityZero
                 | LookupOptions.MustBeInstance | LookupOptions.MustNotBeInstance | LookupOptions.MustBeInvocableIfMember
                 | LookupOptions.MustBeOperator | LookupOptions.MustNotBeMethodTypeParameter)) == 0);