diff --git a/repos/os/include/vfs/dir_file_system.h b/repos/os/include/vfs/dir_file_system.h
index c23ba6a1d6..9afd9897be 100644
--- a/repos/os/include/vfs/dir_file_system.h
+++ b/repos/os/include/vfs/dir_file_system.h
@@ -536,7 +536,7 @@ class Vfs::Dir_file_system : public File_system
 		{
 			path = _sub_path(path);
 			if (!path)
-				return 0;
+				return nullptr;
 
 			if (strlen(path) == 0)
 				return path;
@@ -547,7 +547,7 @@ class Vfs::Dir_file_system : public File_system
 					return leaf_path;
 			}
 
-			return 0;
+			return nullptr;
 		}
 
 		Open_result open(char const  *path,
@@ -686,6 +686,9 @@ class Vfs::Dir_file_system : public File_system
 				return OPENDIR_ERR_LOOKUP_FAILED;
 
 			if (create) {
+				if (leaf_path(path) != nullptr)
+					return OPENDIR_ERR_NODE_ALREADY_EXISTS;
+
 				auto opendir_fn = [&] (File_system &fs, char const *path)
 				{
 					Vfs_handle *tmp_handle;