diff --git a/src/editor/model.js b/src/editor/model.js
index 59371cc3e6..0fbaa4bb3c 100644
--- a/src/editor/model.js
+++ b/src/editor/model.js
@@ -183,15 +183,14 @@ export default class EditorModel {
         if (diff.removed) {
             removedOffsetDecrease = this.removeText(position, diff.removed.length);
         }
-        const canOpenAutoComplete = inputType !== "insertFromPaste" && inputType !== "insertFromDrop";
         let addedLen = 0;
         if (diff.added) {
-            // these shouldn't trigger auto-complete, you just want to append a piece of text
-            addedLen = this._addText(position, diff.added, {validate: canOpenAutoComplete});
+            addedLen = this._addText(position, diff.added, inputType);
         }
         this._mergeAdjacentParts();
         const caretOffset = diff.at - removedOffsetDecrease + addedLen;
         let newPosition = this.positionForOffset(caretOffset, true);
+        const canOpenAutoComplete = inputType !== "insertFromPaste" && inputType !== "insertFromDrop";
         const acPromise = this._setActivePart(newPosition, canOpenAutoComplete);
         if (this._transformCallback) {
             const transformAddedLen = this._transform(newPosition, inputType, diff);
@@ -333,22 +332,20 @@ export default class EditorModel {
      * inserts `str` into the model at `pos`.
      * @param {Object} pos
      * @param {string} str
-     * @param {Object} options
+     * @param {string} inputType the source of the input, see html InputEvent.inputType
      * @param {bool} options.validate Whether characters will be validated by the part.
      *                                Validating allows the inserted text to be parsed according to the part rules.
      * @return {Number} how far from position (in characters) the insertion ended.
      * This can be more than the length of `str` when crossing non-editable parts, which are skipped.
      */
-    _addText(pos, str, {validate=true}) {
+    _addText(pos, str, inputType) {
         let {index} = pos;
         const {offset} = pos;
         let addLen = str.length;
         const part = this._parts[index];
         if (part) {
             if (part.canEdit) {
-                if (validate && part.validateAndInsert(offset, str)) {
-                    str = null;
-                } else if (!validate && part.insert(offset, str)) {
+                if (part.validateAndInsert(offset, str, inputType)) {
                     str = null;
                 } else {
                     const splitPart = part.split(offset);
@@ -367,13 +364,8 @@ export default class EditorModel {
             index = 0;
         }
         while (str) {
-            const newPart = this._partCreator.createPartForInput(str, index);
-            if (validate) {
-                str = newPart.appendUntilRejected(str);
-            } else {
-                newPart.insert(0, str);
-                str = null;
-            }
+            const newPart = this._partCreator.createPartForInput(str, index, inputType);
+            str = newPart.appendUntilRejected(str, inputType);
             this._insertPart(index, newPart);
             index += 1;
         }
diff --git a/src/editor/parts.js b/src/editor/parts.js
index 8d0fe36c28..d14fcf98a2 100644
--- a/src/editor/parts.js
+++ b/src/editor/parts.js
@@ -23,7 +23,7 @@ class BasePart {
         this._text = text;
     }
 
-    acceptsInsertion(chr) {
+    acceptsInsertion(chr, offset, inputType) {
         return true;
     }
 
@@ -56,10 +56,11 @@ class BasePart {
     }
 
     // append str, returns the remaining string if a character was rejected.
-    appendUntilRejected(str) {
+    appendUntilRejected(str, inputType) {
+        const offset = this.text.length;
         for (let i = 0; i < str.length; ++i) {
             const chr = str.charAt(i);
-            if (!this.acceptsInsertion(chr, i)) {
+            if (!this.acceptsInsertion(chr, offset + i, inputType)) {
                 this._text = this._text + str.substr(0, i);
                 return str.substr(i);
             }
@@ -69,10 +70,10 @@ class BasePart {
 
     // inserts str at offset if all the characters in str were accepted, otherwise don't do anything
     // return whether the str was accepted or not.
-    validateAndInsert(offset, str) {
+    validateAndInsert(offset, str, inputType) {
         for (let i = 0; i < str.length; ++i) {
             const chr = str.charAt(i);
-            if (!this.acceptsInsertion(chr)) {
+            if (!this.acceptsInsertion(chr, offset + i, inputType)) {
                 return false;
             }
         }
@@ -82,16 +83,6 @@ class BasePart {
         return true;
     }
 
-    insert(offset, str) {
-        if (this.canEdit) {
-            const beforeInsert = this._text.substr(0, offset);
-            const afterInsert = this._text.substr(offset);
-            this._text = beforeInsert + str + afterInsert;
-            return true;
-        }
-        return false;
-    }
-
     createAutoComplete() {}
 
     trim(len) {
@@ -119,8 +110,15 @@ class BasePart {
 
 // exported for unit tests, should otherwise only be used through PartCreator
 export class PlainPart extends BasePart {
-    acceptsInsertion(chr) {
-        return chr !== "@" && chr !== "#" && chr !== ":" && chr !== "\n";
+    acceptsInsertion(chr, offset, inputType) {
+        if (chr === "\n") {
+            return false;
+        }
+        // when not pasting or dropping text, reject characters that should start a pill candidate
+        if (inputType !== "insertFromPaste" && inputType !== "insertFromDrop") {
+            return chr !== "@" && chr !== "#" && chr !== ":";
+        }
+        return true;
     }
 
     toDOMNode() {
@@ -141,7 +139,6 @@ export class PlainPart extends BasePart {
 
     updateDOMNode(node) {
         if (node.textContent !== this.text) {
-            // console.log("changing plain text from", node.textContent, "to", this.text);
             node.textContent = this.text;
         }
     }
@@ -211,8 +208,8 @@ class PillPart extends BasePart {
 }
 
 class NewlinePart extends BasePart {
-    acceptsInsertion(chr, i) {
-        return (this.text.length + i) === 0 && chr === "\n";
+    acceptsInsertion(chr, offset) {
+        return offset === 0 && chr === "\n";
     }
 
     acceptsRemoval(position, chr) {
@@ -331,11 +328,11 @@ class PillCandidatePart extends PlainPart {
         return this._autoCompleteCreator.create(updateCallback);
     }
 
-    acceptsInsertion(chr, i) {
-        if ((this.text.length + i) === 0) {
+    acceptsInsertion(chr, offset, inputType) {
+        if (offset === 0) {
             return true;
         } else {
-            return super.acceptsInsertion(chr, i);
+            return super.acceptsInsertion(chr, offset, inputType);
         }
     }