diff --git a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
index 856a57c46b7..67b2242c8d9 100644
--- a/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
+++ b/src/services/codefixes/fixClassIncorrectlyImplementsInterface.ts
@@ -25,9 +25,9 @@ namespace ts.codefix {
 
         const result: CodeAction[] = [];
         for (const implementedTypeNode of implementedTypeNodes) {
-            const implementedType = checker.getTypeAtLocation(implementedTypeNode) as InterfaceType;
             // Note that this is ultimately derived from a map indexed by symbol names,
             // so duplicates cannot occur.
+            const implementedType = checker.getTypeAtLocation(implementedTypeNode) as InterfaceType;
             const implementedTypeSymbols = checker.getPropertiesOfType(implementedType);
             const nonPrivateMembers = implementedTypeSymbols.filter(symbol => !(getModifierFlags(symbol.valueDeclaration) & ModifierFlags.Private));