diff --git a/test/00.sqlite-error.js b/test/00.sqlite-error.js
index 924e3c98e..4166a9fae 100644
--- a/test/00.sqlite-error.js
+++ b/test/00.sqlite-error.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const { SqliteError } = require('../.');
 
diff --git a/test/10.database.open.js b/test/10.database.open.js
index 37f28094e..ed80f78cc 100644
--- a/test/10.database.open.js
+++ b/test/10.database.open.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const fs = require('fs');
 const Database = require('../.');
diff --git a/test/11.database.close.js b/test/11.database.close.js
index 8a643ecd3..17a0c88b0 100644
--- a/test/11.database.close.js
+++ b/test/11.database.close.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const util = require('./util');
diff --git a/test/12.database.pragma.js b/test/12.database.pragma.js
index 544c7a64f..1ee86bd0d 100644
--- a/test/12.database.pragma.js
+++ b/test/12.database.pragma.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const util = require('./util');
diff --git a/test/13.database.prepare.js b/test/13.database.prepare.js
index 6f53c028b..c1741c5c5 100644
--- a/test/13.database.prepare.js
+++ b/test/13.database.prepare.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const util = require('./util');
diff --git a/test/14.database.transaction.js b/test/14.database.transaction.js
index dbba6bdf6..34e8090d9 100644
--- a/test/14.database.transaction.js
+++ b/test/14.database.transaction.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const util = require('./util');
diff --git a/test/15.database.exec.js b/test/15.database.exec.js
index 99df9c3df..8b64acc55 100644
--- a/test/15.database.exec.js
+++ b/test/15.database.exec.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const db = new Database(require('./util').next());
diff --git a/test/40.database.checkpoint.js b/test/40.database.checkpoint.js
index d804dc8d5..2f9cd25bb 100644
--- a/test/40.database.checkpoint.js
+++ b/test/40.database.checkpoint.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const fs = require('fs');
 const Database = require('../.');
diff --git a/test/41.database.close.js b/test/41.database.close.js
index 9a67f7cae..3b3593c1f 100644
--- a/test/41.database.close.js
+++ b/test/41.database.close.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const fs = require('fs');
 const Database = require('../.');
diff --git a/test/42.database.register.js b/test/42.database.register.js
index ca1c131a2..6193819a2 100644
--- a/test/42.database.register.js
+++ b/test/42.database.register.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const db = new Database(require('./util').next());
diff --git a/test/43.database.load-extension.js b/test/43.database.load-extension.js
index f6c824b51..31f518638 100644
--- a/test/43.database.load-extension.js
+++ b/test/43.database.load-extension.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Database = require('../.');
 const util = require('./util');
diff --git a/test/50.integers.js b/test/50.integers.js
index 586290a1d..35cbe28d1 100644
--- a/test/50.integers.js
+++ b/test/50.integers.js
@@ -1,3 +1,4 @@
+'use strict';
 const { expect } = require('chai');
 const Integer = require('integer');
 const Database = require('../.');