diff --git a/crates/base_db/src/lib.rs b/crates/base_db/src/lib.rs
index 3e0b6637d2..55ef9fc24d 100644
--- a/crates/base_db/src/lib.rs
+++ b/crates/base_db/src/lib.rs
@@ -167,29 +167,23 @@ impl<T: SourceDatabaseExt> FileLoader for FileLoaderDelegate<&'_ T> {
     }
 
     fn possible_sudmobule_names(&self, module_file: FileId) -> Vec<String> {
-        fn possible_sudmobules_opt(
-            module_files: &FileSet,
-            module_file: FileId,
-        ) -> Option<Vec<FileId>> {
-            match module_files.file_name_and_extension(module_file)? {
-                ("mod", Some("rs")) | ("lib", Some("rs")) => {
-                    module_files.list_files(module_file, None)
-                }
-                (directory_with_module_name, Some("rs")) => module_files
-                    .list_files(module_file, Some(&format!("../{}/", directory_with_module_name))),
-                _ => None,
-            }
-        }
-
         let module_files = &self.source_root(module_file).file_set;
-        possible_sudmobules_opt(module_files, module_file)
-            .unwrap_or_default()
+        let possible_submodule_files = match module_files.file_name_and_extension(module_file) {
+            Some(("mod", Some("rs"))) | Some(("lib", Some("rs"))) => {
+                module_files.list_files_with_extensions(module_file, None)
+            }
+            Some((directory_with_module_name, Some("rs"))) => module_files
+                .list_files_with_extensions(
+                    module_file,
+                    Some(&format!("../{}/", directory_with_module_name)),
+                ),
+            _ => Vec::new(),
+        };
+
+        possible_submodule_files
             .into_iter()
-            .filter_map(|submodule_file| module_files.file_name_and_extension(submodule_file))
-            .map(|(file_name, extension)| match extension {
-                Some(extension) => format!("{}.{}", file_name, extension),
-                None => file_name.to_owned(),
-            })
+            .filter(|(_, extension)| extension == &Some("rs"))
+            .map(|(file_name, _)| file_name.to_owned())
             .collect()
     }
 }
diff --git a/crates/vfs/src/file_set.rs b/crates/vfs/src/file_set.rs
index 956cffb29b..3085fd8189 100644
--- a/crates/vfs/src/file_set.rs
+++ b/crates/vfs/src/file_set.rs
@@ -30,33 +30,33 @@ impl FileSet {
         self.paths[&file].file_name_and_extension()
     }
 
-    pub fn list_files(
+    pub fn list_files_with_extensions(
         &self,
         anchor: FileId,
         anchor_relative_path: Option<&str>,
-    ) -> Option<Vec<FileId>> {
+    ) -> Vec<(&str, Option<&str>)> {
         let anchor_directory = {
             let path = self.paths[&anchor].clone();
             match anchor_relative_path {
                 Some(anchor_relative_path) => path.join(anchor_relative_path),
                 None => path.parent(),
             }
-        }?;
+        };
 
-        Some(
+        if let Some(anchor_directory) = anchor_directory {
             self.paths
                 .iter()
-                .filter_map(|(&file_id, path)| {
-                    if path.parent()? == anchor_directory
-                        && matches!(path.file_name_and_extension(), Some((_, Some("rs"))))
-                    {
-                        Some(file_id)
+                .filter_map(|(_, path)| {
+                    if path.parent()? == anchor_directory {
+                        path.file_name_and_extension()
                     } else {
                         None
                     }
                 })
-                .collect(),
-        )
+                .collect()
+        } else {
+            Vec::new()
+        }
     }
     pub fn insert(&mut self, file_id: FileId, path: VfsPath) {
         self.files.insert(path.clone(), file_id);