diff --git a/src/services/codefixes/helpers.ts b/src/services/codefixes/helpers.ts
index 4564a571b1f43..de474f57c7954 100644
--- a/src/services/codefixes/helpers.ts
+++ b/src/services/codefixes/helpers.ts
@@ -50,6 +50,7 @@ namespace ts.codefix {
         importAdder: ImportAdder | undefined,
         addClassElement: (node: AddNode) => void,
         body: Block | undefined,
+        preserveOptional = true,
         isAmbient = false,
     ): void {
         const declarations = symbol.getDeclarations();
@@ -63,7 +64,7 @@ namespace ts.codefix {
         const visibilityModifier = createVisibilityModifier(getEffectiveModifierFlags(declaration));
         const modifiers = visibilityModifier ? factory.createNodeArray([visibilityModifier]) : undefined;
         const type = checker.getWidenedType(checker.getTypeOfSymbolAtLocation(symbol, enclosingDeclaration));
-        const optional = !!(symbol.flags & SymbolFlags.Optional);
+        const optional = preserveOptional && !!(symbol.flags & SymbolFlags.Optional);
         const ambient = !!(enclosingDeclaration.flags & NodeFlags.Ambient) || isAmbient;
         const quotePreference = getQuotePreference(sourceFile, preferences);
 
diff --git a/src/services/completions.ts b/src/services/completions.ts
index c70efda3f34e7..f86c30777523d 100644
--- a/src/services/completions.ts
+++ b/src/services/completions.ts
@@ -888,7 +888,7 @@ namespace ts.Completions {
             node => {
                 let requiredModifiers = ModifierFlags.None;
                 if (isAbstract) {
-                        requiredModifiers |= ModifierFlags.Abstract;
+                    requiredModifiers |= ModifierFlags.Abstract;
                 }
                 if (isClassElement(node)
                     && checker.getMemberOverrideModifierStatus(classLikeDeclaration, node) === MemberOverrideStatus.NeedsOverride) {
@@ -912,6 +912,7 @@ namespace ts.Completions {
                 completionNodes.push(node);
             },
             body,
+            /*preserveOptional*/ false,
             isAbstract);
 
         if (completionNodes.length) {
@@ -3882,5 +3883,6 @@ namespace ts.Completions {
         }
         return charCode;
     }
+
 }
 
diff --git a/tests/cases/fourslash/completionsOverridingMethod9.ts b/tests/cases/fourslash/completionsOverridingMethod9.ts
new file mode 100644
index 0000000000000..0be512f698801
--- /dev/null
+++ b/tests/cases/fourslash/completionsOverridingMethod9.ts
@@ -0,0 +1,44 @@
+/// <reference path="fourslash.ts" />
+
+// @Filename: a.ts
+// @newline: LF
+
+////interface IFoo {
+////    a?: number;
+////    b?(x: number): void;
+////}
+////class Foo implements IFoo {
+////    /**/
+////}
+
+verify.completions({
+    marker: "",
+    isNewIdentifierLocation: true,
+    preferences: {
+        includeCompletionsWithInsertText: true,
+        includeCompletionsWithSnippetText: false,
+        includeCompletionsWithClassMemberSnippets: true,
+    },
+    includes: [
+        {
+            name: "a",
+            sortText: completion.SortText.LocationPriority,
+            replacementSpan: {
+                fileName: "",
+                pos: 0,
+                end: 0,
+            },
+            insertText: "a: number;\n"
+        },
+        {
+            name: "b",
+            sortText: completion.SortText.LocationPriority,
+            replacementSpan: {
+                fileName: "",
+                pos: 0,
+                end: 0,
+            },
+            insertText: "b(x: number): void {\n}\n"
+        },
+    ],
+});