diff --git a/src/createVelocityContext.js b/src/createVelocityContext.js
index 7a747b7cd..690613db1 100644
--- a/src/createVelocityContext.js
+++ b/src/createVelocityContext.js
@@ -9,7 +9,7 @@ function escapeJavaScript(x) {
   if (typeof x === 'string') return jsEscapeString(x).replace(/\\n/g, '\n'); // See #26,
   if (isPlainObject(x)) {
     const result = {};
-    for (let key in x) { // eslint-disable-line prefer-const
+    for (const key in x) { // eslint-disable-line prefer-const
       result[key] = jsEscapeString(x[key]);
     }
 
diff --git a/src/renderVelocityTemplateObject.js b/src/renderVelocityTemplateObject.js
index ed5fcb756..16c689025 100644
--- a/src/renderVelocityTemplateObject.js
+++ b/src/renderVelocityTemplateObject.js
@@ -64,7 +64,7 @@ module.exports = function renderVelocityTemplateObject(templateObject, context)
 
   // Let's check again
   if (isPlainObject(toProcess)) {
-    for (let key in toProcess) { // eslint-disable-line prefer-const
+    for (const key in toProcess) { // eslint-disable-line prefer-const
 
       const value = toProcess[key];
       debugLog('Processing key:', key, '- value:', value);
diff --git a/src/utils.js b/src/utils.js
index 9ba07d491..db799f90a 100644
--- a/src/utils.js
+++ b/src/utils.js
@@ -28,7 +28,7 @@ module.exports = {
 
   capitalizeKeys: o => {
     const capitalized = {};
-    for (let key in o) { // eslint-disable-line prefer-const
+    for (const key in o) { // eslint-disable-line prefer-const
       capitalized[key.replace(/((?:^|-)[a-z])/g, x => x.toUpperCase())] = o[key];
     }