diff --git a/vendors/squire/build/squire-raw.js b/vendors/squire/build/squire-raw.js
index 8fae8f5bf..1d0b198b0 100644
--- a/vendors/squire/build/squire-raw.js
+++ b/vendors/squire/build/squire-raw.js
@@ -1012,8 +1012,13 @@ const
 	rangeDoesStartAtBlockBoundary = ( range, root ) => {
 		let startContainer = range.startContainer;
 		let startOffset = range.startOffset;
+		let startBlock = getStartBlockOfRange( range, root );
 		let nodeAfterCursor;
 
+		if (!startBlock) {
+			return false;
+		}
+
 		// If in the middle or end of a text node, we're not at the boundary.
 		if ( startContainer.nodeType === TEXT_NODE ) {
 			if ( startOffset ) {