diff --git a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs
index 26f7a50692780259f407e1f0a508ea439f5ded7e..96f63f13ec273d444a9261a45d782745c2d2caad 100644
--- a/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs
+++ b/src/Compilers/CSharp/Portable/Symbols/Source/SourceMemberMethodSymbol.cs
@@ -95,14 +95,15 @@ internal sealed class SourceMemberMethodSymbol : SourceMethodSymbol
 
             this.MakeFlags(methodKind, declarationModifiers, returnsVoid, isExtensionMethod, isMetadataVirtualIgnoringModifiers);
 
-            _typeParameters = syntax.Arity == 0
-                ? ImmutableArray<TypeParameterSymbol>.Empty
-                : MakeTypeParameters(syntax, diagnostics);
-
             if (syntax.Arity == 0)
             {
+                _typeParameters = ImmutableArray<TypeParameterSymbol>.Empty;
                 ReportErrorIfHasConstraints(syntax.ConstraintClauses, diagnostics);
             }
+            else
+            {
+                _typeParameters = MakeTypeParameters(syntax, diagnostics);
+            }
 
             bool hasBlockBody = syntax.Body != null;
             _isExpressionBodied = !hasBlockBody && syntax.ExpressionBody != null;