diff --git a/src/Buffer.cpp b/src/Buffer.cpp
index e3cd6ac24c..77c815196b 100644
--- a/src/Buffer.cpp
+++ b/src/Buffer.cpp
@@ -3583,8 +3583,12 @@ void Buffer::listMacroNames(MacroNameSet & macros) const
 	// loop over children
 	Impl::BufferPositionMap::iterator it = d->children_positions.begin();
 	Impl::BufferPositionMap::iterator end = d->children_positions.end();
-	for (; it != end; ++it)
-		it->first->listMacroNames(macros);
+	for (; it != end; ++it) {
+		Buffer * child = const_cast<Buffer *>(it->first);
+		// The buffer might have been closed (see #10766).
+		if (theBufferList().isLoaded(child))
+			child->listMacroNames(macros);
+	}
 
 	// call parent
 	Buffer const * const pbuf = d->parent();
diff --git a/status.22x b/status.22x
index 5753b32c5a..91a8a3ec63 100644
--- a/status.22x
+++ b/status.22x
@@ -78,6 +78,9 @@ What's new
 - Fix crash when closing master document with dirty child while Document
   Settings dialog is open (bug 9979).
 
+- Fix crash when closing master with children and grandchildren
+  (bug 10766).
+
 - Fix random crash when dissolving inset (bug 10667).
 
 - Fix potential crash when cursor enters an inset (bug 10691).