diff --git a/lib/helpers/chopfile.js b/lib/helpers/chopfile.js
new file mode 100644
index 0000000..7afe327
--- /dev/null
+++ b/lib/helpers/chopfile.js
@@ -0,0 +1,34 @@
+const fs = require('fs');
+
+module.exports = {
+  chopByFileSizeSync(filePath, encoding, chunkSize) {
+    const file = fs.readFileSync(filePath, encoding);
+    var chunks = Math.ceil(fs.statSync(filePath).size / chunkSize, chunkSize);
+    var chunk = 0;
+    const files = [];
+    while (chunk <= chunks) {
+      var offset = chunk * chunkSize;
+      files.push((file.slice(offset, offset + chunkSize)));
+      chunk++;
+    }
+    return files.filter(v => v);
+  },
+  chopByFileSizeAsync(filePath, encoding, chunkSize) {
+    return new Promise((resolve, reject) => {
+      fs.readFile(filePath, encoding, (error, file) => {
+        if (error) {
+          return reject(error);
+        }
+        var chunks = Math.ceil(fs.statSync(filePath).size / chunkSize, chunkSize);
+        var chunk = 0;
+        const files = [];
+        while (chunk <= chunks) {
+          var offset = chunk * chunkSize;
+          files.push((file.slice(offset, offset + chunkSize)));
+          chunk++;
+        }
+        return resolve(files.filter(v => v));
+      });
+    });
+  }
+}
diff --git a/lib/helpers/parse-config.js b/lib/helpers/parse-config.js
index 41d87a1..20e5c3c 100644
--- a/lib/helpers/parse-config.js
+++ b/lib/helpers/parse-config.js
@@ -13,6 +13,7 @@ const defaults = {
   verbose: false,
   quiet: false,
   dry: false,
+  chunkSize: 300 * 300,
   glob: {},
   cwd: null,
 };
diff --git a/lib/helpers/replace-async.js b/lib/helpers/replace-async.js
index 5167d4b..0368314 100644
--- a/lib/helpers/replace-async.js
+++ b/lib/helpers/replace-async.js
@@ -5,41 +5,40 @@
  */
 const fs = require('fs');
 const makeReplacements = require('./make-replacements');
+const chopByFileSize = require('./chopfile').chopByFileSizeAsync;
 
 /**
  * Helper to replace in a single file (async)
  */
-module.exports = function replaceAsync(file, from, to, config) {
+module.exports = function replaceAsync(filePath, from, to, config) {
 
   //Extract relevant config
-  const {encoding, dry, countMatches} = config;
+  const { encoding, dry, countMatches, chunkSize } = config;
 
   //Wrap in promise
   return new Promise((resolve, reject) => {
-    fs.readFile(file, encoding, (error, contents) => {
-      //istanbul ignore if
-      if (error) {
-        return reject(error);
-      }
-
-      //Make replacements
-      const [result, newContents] = makeReplacements(
-        contents, from, to, file, countMatches
-      );
-
+    chopByFileSize(filePath, encoding, chunkSize).then(chunks => {
+      let result = [];
+      chunks.forEach((chunk, i) => {
+        //Make replacements
+        const response = makeReplacements(
+          chunk, from, to, chunk, countMatches
+        );
+        chunks[i] = response[1];
+        result.push(response[0].hasChanged);
+      });
       //Not changed or dry run?
-      if (!result.hasChanged || dry) {
+      if (result.filter(v => v).length === 0 || dry) {
         return resolve(result);
       }
-
       //Write to file
-      fs.writeFile(file, newContents, encoding, error => {
+      fs.writeFile(filePath, chunks.join(''), encoding, error => {
         //istanbul ignore if
         if (error) {
           return reject(error);
         }
         resolve(result);
       });
-    });
+    }, err => reject(err));
   });
-};
+}
diff --git a/lib/helpers/replace-sync.js b/lib/helpers/replace-sync.js
index ada3519..f4d4ff3 100644
--- a/lib/helpers/replace-sync.js
+++ b/lib/helpers/replace-sync.js
@@ -5,26 +5,30 @@
  */
 const fs = require('fs');
 const makeReplacements = require('./make-replacements');
+const chopByFileSize = require('./chopfile').chopByFileSizeSync;
 
 /**
  * Helper to replace in a single file (sync)
  */
-module.exports = function replaceSync(file, from, to, config) {
-
+  module.exports = function replaceSync(filePath, from, to, config) {
   //Extract relevant config and read file contents
-  const {encoding, dry, countMatches} = config;
-  const contents = fs.readFileSync(file, encoding);
-
-  //Replace contents and check if anything changed
-  const [result, newContents] = makeReplacements(
-    contents, from, to, file, countMatches
-  );
+  const { encoding, dry, countMatches, chunkSize } = config;
+  const chunks = chopByFileSize(filePath, encoding, chunkSize);
+  let result;
+  let newContents;
+  chunks.forEach((chunk, i) => {
 
-  //Contents changed and not a dry run? Write to file
-  if (result.hasChanged && !dry) {
-    fs.writeFileSync(file, newContents, encoding);
-  }
+    //Replace contents and check if anything changed
+    [result, newContents] = makeReplacements(
+      chunk, from, to, chunk, countMatches
+    );
 
+    //Contents changed and not a dry run? Write to file
+    if (result.hasChanged && !dry) {
+      chunks[i] = newContents;
+    }
+  });
+  fs.writeFileSync(filePath, chunks.join(''), encoding);
   //Return result
   return result;
 };