diff --git a/src/@types/diff-dom.ts b/src/@types/diff-dom.ts
index 884ee6126d..38ff6432cf 100644
--- a/src/@types/diff-dom.ts
+++ b/src/@types/diff-dom.ts
@@ -15,20 +15,8 @@ limitations under the License.
 */
 
 declare module "diff-dom" {
-    enum Action {
-        AddElement = "addElement",
-        AddTextElement = "addTextElement",
-        RemoveTextElement = "removeTextElement",
-        RemoveElement = "removeElement",
-        ReplaceElement = "replaceElement",
-        ModifyTextElement = "modifyTextElement",
-        AddAttribute = "addAttribute",
-        RemoveAttribute = "removeAttribute",
-        ModifyAttribute = "modifyAttribute",
-    }
-
     export interface IDiff {
-        action: Action;
+        action: string;
         name: string;
         text?: string;
         route: number[];
diff --git a/src/utils/MessageDiffUtils.tsx b/src/utils/MessageDiffUtils.tsx
index b5d5e31432..f3dc1320dc 100644
--- a/src/utils/MessageDiffUtils.tsx
+++ b/src/utils/MessageDiffUtils.tsx
@@ -149,7 +149,7 @@ function stringAsTextNode(string: string): Text {
 function renderDifferenceInDOM(originalRootNode: Node, diff: IDiff, diffMathPatch: DiffMatchPatch): void {
     const {refNode, refParentNode} = findRefNodes(originalRootNode, diff.route);
     switch (diff.action) {
-        case Action.ReplaceElement: {
+        case "replaceElement": {
             const container = document.createElement("span");
             const delNode = wrapDeletion(diffTreeToDOM(diff.oldValue));
             const insNode = wrapInsertion(diffTreeToDOM(diff.newValue));
@@ -158,17 +158,17 @@ function renderDifferenceInDOM(originalRootNode: Node, diff: IDiff, diffMathPatc
             refNode.parentNode.replaceChild(container, refNode);
             break;
         }
-        case Action.RemoveTextElement: {
+        case "removeTextElement": {
             const delNode = wrapDeletion(stringAsTextNode(diff.value));
             refNode.parentNode.replaceChild(delNode, refNode);
             break;
         }
-        case Action.RemoveElement: {
+        case "removeElement": {
             const delNode = wrapDeletion(diffTreeToDOM(diff.element));
             refNode.parentNode.replaceChild(delNode, refNode);
             break;
         }
-        case Action.ModifyTextElement: {
+        case "modifyTextElement": {
             const textDiffs = diffMathPatch.diff_main(diff.oldValue, diff.newValue);
             diffMathPatch.diff_cleanupSemantic(textDiffs);
             const container = document.createElement("span");
@@ -184,12 +184,12 @@ function renderDifferenceInDOM(originalRootNode: Node, diff: IDiff, diffMathPatc
             refNode.parentNode.replaceChild(container, refNode);
             break;
         }
-        case Action.AddElement: {
+        case "addElement": {
             const insNode = wrapInsertion(diffTreeToDOM(diff.element));
             insertBefore(refParentNode, refNode, insNode);
             break;
         }
-        case Action.AddTextElement: {
+        case "addTextElement": {
             // XXX: sometimes diffDOM says insert a newline when there shouldn't be one
             // but we must insert the node anyway so that we don't break the route child IDs.
             // See https://github.com/fiduswriter/diffDOM/issues/100
@@ -199,9 +199,9 @@ function renderDifferenceInDOM(originalRootNode: Node, diff: IDiff, diffMathPatc
         }
         // e.g. when changing a the href of a link,
         // show the link with old href as removed and with the new href as added
-        case Action.RemoveAttribute:
-        case Action.AddAttribute:
-        case Action.ModifyAttribute: {
+        case "removeAttribute":
+        case "addAttribute":
+        case "modifyAttribute": {
             const delNode = wrapDeletion(refNode.cloneNode(true));
             const updatedNode = refNode.cloneNode(true) as HTMLElement;
             if (diff.action === "addAttribute" || diff.action === "modifyAttribute") {