diff --git a/core/editor.js b/core/editor.js
index f70b523413..f3560234be 100644
--- a/core/editor.js
+++ b/core/editor.js
@@ -207,13 +207,13 @@ class Editor {
       const oldValue = mutations[0].oldValue.replace(CursorBlot.CONTENTS, '');
       const oldText = new Delta().insert(oldValue);
       const newText = new Delta().insert(textBlot.value());
-      const relativeSelectionInfo = selectionInfo && [
-        new Range(selectionInfo[0].index - index, selectionInfo[0].length),
-        new Range(selectionInfo[1].index - index, selectionInfo[1].length),
-      ];
+      const relativeSelectionInfo = selectionInfo && {
+        oldRange: shiftRange(selectionInfo.oldRange, -index),
+        newRange: shiftRange(selectionInfo.newRange, -index),
+      };
       const diffDelta = new Delta()
         .retain(index)
-        .concat(diffDeltas(oldText, newText, relativeSelectionInfo));
+        .concat(oldText.diff(newText, relativeSelectionInfo));
       change = diffDelta.reduce((delta, op) => {
         if (op.insert) {
           return delta.insert(op.insert, formats);
@@ -224,7 +224,7 @@ class Editor {
     } else {
       this.delta = this.getDelta();
       if (!change || !equal(oldDelta.compose(change), this.delta)) {
-        change = diffDeltas(oldDelta, this.delta, selectionInfo);
+        change = oldDelta.diff(this.delta, selectionInfo);
       }
     }
     return change;
@@ -339,84 +339,8 @@ function normalizeDelta(delta) {
   }, new Delta());
 }
 
-function splitDelta(delta, index) {
-  return [delta.slice(0, index), delta.slice(index)];
-}
-
-function diffDeltas(oldDelta, newDelta, selectionInfo = undefined) {
-  if (selectionInfo == null) {
-    return oldDelta.diff(newDelta);
-  }
-
-  // generate better diffs than Delta#diff by taking into account the
-  // old and new selection.  for example, a text change from "xxx" to "xx"
-  // could be a delete or forwards-delete of any one of the x's, or the
-  // result of selecting two of the x's and typing "x".
-  const [oldSelection, newSelection] = selectionInfo;
-  const oldDeltaLength = oldDelta.length();
-  const newDeltaLength = newDelta.length();
-  if (oldSelection.length === 0 && newSelection.length === 0) {
-    // see if we have an insert or delete before or after cursor
-    const oldCursor = oldSelection.index;
-    const newCursor = newSelection.index;
-    const [oldBefore, oldAfter] = splitDelta(oldDelta, oldCursor);
-    const [newBefore, newAfter] = splitDelta(newDelta, newCursor);
-    if (equal(oldAfter, newAfter)) {
-      const prefixLength = Math.min(oldCursor, newCursor);
-      const [oldPrefix, oldMiddle] = splitDelta(oldBefore, prefixLength);
-      const [newPrefix, newMiddle] = splitDelta(newBefore, prefixLength);
-      if (equal(oldPrefix, newPrefix)) {
-        // insert or delete right before cursor
-        return new Delta()
-          .retain(prefixLength)
-          .concat(oldMiddle.diff(newMiddle));
-      }
-    } else if (equal(oldBefore, newBefore)) {
-      const suffixLength = Math.min(
-        oldDeltaLength - oldCursor,
-        newDeltaLength - newCursor,
-      );
-      const [oldMiddle, oldSuffix] = splitDelta(
-        oldAfter,
-        oldDeltaLength - oldCursor - suffixLength,
-      );
-      const [newMiddle, newSuffix] = splitDelta(
-        newAfter,
-        newDeltaLength - newCursor - suffixLength,
-      );
-      if (equal(oldSuffix, newSuffix)) {
-        // insert or delete right after cursor
-        return new Delta().retain(oldCursor).concat(oldMiddle.diff(newMiddle));
-      }
-    }
-  }
-  if (oldSelection.length > 0 && newSelection.length === 0) {
-    // see if diff could be a splice of the old selection range
-    const oldPrefix = oldDelta.slice(0, oldSelection.index);
-    const oldSuffix = oldDelta.slice(oldSelection.index + oldSelection.length);
-    const prefixLength = oldPrefix.length();
-    const suffixLength = oldSuffix.length();
-    if (newDeltaLength >= prefixLength + suffixLength) {
-      const newPrefix = newDelta.slice(0, prefixLength);
-      const newSuffix = newDelta.slice(newDeltaLength - suffixLength);
-      if (equal(oldPrefix, newPrefix) && equal(oldSuffix, newSuffix)) {
-        const oldMiddle = oldDelta.slice(
-          prefixLength,
-          oldDeltaLength - suffixLength,
-        );
-        const newMiddle = newDelta.slice(
-          prefixLength,
-          newDeltaLength - suffixLength,
-        );
-        return new Delta()
-          .retain(prefixLength)
-          .concat(newMiddle)
-          .delete(oldMiddle.length());
-      }
-    }
-  }
-
-  return oldDelta.diff(newDelta);
+function shiftRange({ index, length }, amount) {
+  return new Range(index + amount, length);
 }
 
 export default Editor;
diff --git a/core/quill.js b/core/quill.js
index 7fc4652f81..024f64b938 100644
--- a/core/quill.js
+++ b/core/quill.js
@@ -105,7 +105,7 @@ class Quill {
       const oldRange = this.selection.lastRange;
       const [newRange] = this.selection.getRange();
       const selectionInfo =
-        oldRange && newRange ? [oldRange, newRange] : undefined;
+        oldRange && newRange ? { oldRange, newRange } : undefined;
       modify.call(
         this,
         () => this.editor.update(null, mutations, selectionInfo),
diff --git a/package-lock.json b/package-lock.json
index b6f9544515..07a140f4d6 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4007,7 +4007,8 @@
     "fast-diff": {
       "version": "1.1.2",
       "resolved": "https://registry.npmjs.org/fast-diff/-/fast-diff-1.1.2.tgz",
-      "integrity": "sha512-KaJUt+M9t1qaIteSvjc6P3RbMdXsNhK61GRftR6SNxqmhthcd9MGIi4T+o0jD8LUSpSnSKXE20nLtJ3fOHxQig=="
+      "integrity": "sha512-KaJUt+M9t1qaIteSvjc6P3RbMdXsNhK61GRftR6SNxqmhthcd9MGIi4T+o0jD8LUSpSnSKXE20nLtJ3fOHxQig==",
+      "dev": true
     },
     "fast-json-stable-stringify": {
       "version": "2.0.0",
@@ -7482,13 +7483,18 @@
       "dev": true
     },
     "quill-delta": {
-      "version": "4.0.1",
-      "resolved": "https://registry.npmjs.org/quill-delta/-/quill-delta-4.0.1.tgz",
-      "integrity": "sha512-8MdJmDlsnkGTMP3VVqVb/S95l+X691/xY1iQ3tmDDBWkqUyqh72+tBnaEStxfEa5YqzozGeYWz8j2B3pni5Bew==",
+      "version": "4.1.0",
+      "resolved": "github:quilljs/delta#cc5e690e389f8f7623c8ab42341064a05c76b433",
       "requires": {
         "deep-equal": "^1.0.1",
         "extend": "^3.0.2",
-        "fast-diff": "1.1.2"
+        "fast-diff": "github:jhchen/fast-diff#f4e19f4486123086679ee2c8f703efb44dfb2499"
+      },
+      "dependencies": {
+        "fast-diff": {
+          "version": "github:jhchen/fast-diff#f4e19f4486123086679ee2c8f703efb44dfb2499",
+          "from": "github:jhchen/fast-diff#f4e19f4486123086679ee2c8f703efb44dfb2499"
+        }
       }
     },
     "randombytes": {
diff --git a/package.json b/package.json
index 4fb13d43e4..67242780c0 100644
--- a/package.json
+++ b/package.json
@@ -37,7 +37,7 @@
     "eventemitter3": "^3.1.0",
     "extend": "^3.0.2",
     "parchment": "quilljs/parchment#2674d396d363e3b4668111590426405e3754d1a0",
-    "quill-delta": "4.0.1"
+    "quill-delta": "4.1.0"
   },
   "devDependencies": {
     "babel-core": "^6.26.3",