diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-left.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-left.js
index 631cb72fcd..e9ae376fef 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-left.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-left.js
@@ -1,3 +1,5 @@
+"use strict";
+
 const obj = {
   a: {
     b: 0,
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-right.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-right.js
index d2299449ff..58d99d7927 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-right.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/assignment-right.js
@@ -1,3 +1,5 @@
+"use strict";
+
 const obj = {
   a: {
     b: {
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/call.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/call.js
index 846b15d7dc..b3c044c519 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/call.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/call.js
@@ -1,3 +1,5 @@
+"use strict";
+
 let calls = 0;
 const obj = {
   a: {
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/delete.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/delete.js
index cbb890e5fe..a397021233 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/delete.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/delete.js
@@ -1,3 +1,5 @@
+"use strict";
+
 const obj = {
   a: {
     b: 0,
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/new.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/new.js
index bef413aa6e..184524f49e 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/new.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/new.js
@@ -1,3 +1,5 @@
+"use strict";
+
 let calls = 0;
 const obj = {
   a: {
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/unary.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/unary.js
index 8d71fe89c7..f8a55d8646 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/unary.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/unary.js
@@ -1,3 +1,5 @@
+"use strict";
+
 const obj = {
   a: {
     b: 0,
diff --git a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/update.js b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/update.js
index 06d1024e4d..320a8c75e0 100644
--- a/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/update.js
+++ b/packages/babel-plugin-transform-optional-chaining/test/fixtures/execute/update.js
@@ -1,3 +1,5 @@
+"use strict";
+
 const obj = {
   a: {
     b: 0,