diff --git a/app/src/protyle/toolbar/InlineMath.ts b/app/src/protyle/toolbar/InlineMath.ts
index 663a9c09e..671014033 100644
--- a/app/src/protyle/toolbar/InlineMath.ts
+++ b/app/src/protyle/toolbar/InlineMath.ts
@@ -17,7 +17,7 @@ export class InlineMath extends ToolbarItem {
                 return;
             }
             let mathElement = hasClosestByAttribute(range.startContainer, "data-type", "inline-math") as Element;
-            if (!mathElement && range.startContainer.nodeType !== 3) {
+            if (!mathElement && range.startContainer.nodeType !== 3 && range.startContainer.childNodes[range.startOffset]) {
                 const previousSibling = hasPreviousSibling(range.startContainer.childNodes[range.startOffset]) as HTMLElement;
                 if (previousSibling && previousSibling.getAttribute("data-type").indexOf("inline-math") > -1) {
                     mathElement = previousSibling;