diff --git a/src/utils/applyChangeToValue.js b/src/utils/applyChangeToValue.js
index 9d499651..fdbaba12 100644
--- a/src/utils/applyChangeToValue.js
+++ b/src/utils/applyChangeToValue.js
@@ -13,11 +13,11 @@ const applyChangeToValue = (
   let oldPlainTextValue = getPlainText(value, config)
 
   let lengthDelta = oldPlainTextValue.length - plainTextValue.length
-  if (selectionStartBefore === null) {
+  if (selectionStartBefore === 'undefined') {
     selectionStartBefore = selectionEndAfter + lengthDelta
   }
 
-  if (selectionEndBefore === null) {
+  if (selectionEndBefore === 'undefined') {
     selectionEndBefore = selectionStartBefore
   }
 
@@ -60,16 +60,22 @@ const applyChangeToValue = (
 
       // find start of diff
       spliceStart = 0
-      while (plainTextValue[spliceStart] === controlPlainTextValue[spliceStart])
+      while (plainTextValue[spliceStart] === oldPlainTextValue[spliceStart])
         spliceStart++
 
+      // find end of diff
+      let spliceEndOfNew = plainTextValue.length
+      let spliceEndOfOld = oldPlainTextValue.length
+      while (plainTextValue[spliceEndOfNew -1] === oldPlainTextValue[spliceEndOfOld - 1]) {
+        spliceEndOfNew--
+        spliceEndOfOld--
+      }
+
       // extract auto-corrected insertion
-      insert = plainTextValue.slice(spliceStart, selectionEndAfter)
+      insert = plainTextValue.slice(spliceStart, spliceEndOfNew)
 
       // find index of the unchanged remainder
-      spliceEnd = oldPlainTextValue.lastIndexOf(
-        plainTextValue.substring(selectionEndAfter)
-      )
+      spliceEnd = spliceEndOfOld >= spliceStart ? spliceEndOfOld : selectionEndAfter
 
       // re-map the corrected indices
       mappedSpliceStart = mapPlainTextIndex(value, config, spliceStart, 'START')
diff --git a/src/utils/applyChangeToValue.spec.js b/src/utils/applyChangeToValue.spec.js
index 06f6850e..44226814 100644
--- a/src/utils/applyChangeToValue.spec.js
+++ b/src/utils/applyChangeToValue.spec.js
@@ -70,6 +70,49 @@ describe('#applyChangeToValue', () => {
     )
   })
 
+  it('should correctly add characters with cursor in the middle at the end, beginning, and in the middle of text', () => {
+    let changed = 'S[start]' + plainText
+    let result = applyChangeToValue(
+      value,
+      changed,
+      {
+        selectionStartBefore: 0,
+        selectionEndBefore: 0,
+        selectionEndAfter: 1,
+      },
+      config
+    )
+    expect(result).toEqual('S[start]' + value)
+
+    changed = plainText + 'E[end]'
+    result = applyChangeToValue(
+      value,
+      changed,
+      {
+        selectionStartBefore: plainText.length,
+        selectionEndBefore: plainText.length,
+        selectionEndAfter: plainText.length + 1,
+      },
+      config
+    )
+    expect(result).toEqual(value + 'E[end]')
+
+    changed = "Hi John Doe, \n\nlet's M[mid]add joe@smoe.com to this conversation..."
+    result = applyChangeToValue(
+      value,
+      changed,
+      {
+        selectionStartBefore: 21,
+        selectionEndBefore: 21,
+        selectionEndAfter: 22,
+      },
+      config
+    )
+    expect(result).toEqual(
+      "Hi @[John Doe](user:johndoe), \n\nlet's M[mid]add @[joe@smoe.com](email:joe@smoe.com) to this conversation..."
+    )
+  })
+
   it('should correctly delete single characters and ranges of selected text', () => {
     // delete "i"
     let changed =
@@ -133,6 +176,20 @@ describe('#applyChangeToValue', () => {
       config
     )
     expect(result).toEqual(value.replace('add', 'remove'))
+
+    // replace range with cursor in the middle, eg. remove|[remove]
+    changed = plainText.replace('add', 'remove[remove]')
+    result = applyChangeToValue(
+      value,
+      changed,
+      {
+        selectionStartBefore: plainText.indexOf('add'),
+        selectionEndBefore: plainText.indexOf('add') + 'add'.length,
+        selectionEndAfter: plainText.indexOf('add') + 'remove'.length,
+      },
+      config
+    )
+    expect(result).toEqual(value.replace('add', 'remove[remove]'))
   })
 
   it('should remove mentions markup contained in deleted text ranges', () => {
@@ -257,7 +314,7 @@ describe('#applyChangeToValue', () => {
   })
 
   it('should correctly handle text auto-correction', () => {
-    const result = applyChangeToValue(
+    let result = applyChangeToValue(
       'ill',
       "I'll",
       {
@@ -268,5 +325,20 @@ describe('#applyChangeToValue', () => {
       config
     )
     expect(result).toEqual("I'll")
+
+    // case like
+    // input queue: s -> a -> d
+    // IME queue(| is the cursor position): s|[sa] -> s'a|[sa'a] -> sad|[sad]
+    result = applyChangeToValue(
+      "s'a[sa'a]",
+      "sad[sad]",
+      {
+        selectionStartBefore: 2,
+        selectionEndBefore: 2,
+        selectionEndAfter: 3,
+      },
+      config
+    )
+    expect(result).toEqual("sad[sad]")
   })
 })