diff --git a/crates/ra_hir/src/test_db.rs b/crates/ra_hir/src/test_db.rs
index 5237b303af4..1caa2e8759d 100644
--- a/crates/ra_hir/src/test_db.rs
+++ b/crates/ra_hir/src/test_db.rs
@@ -81,7 +81,7 @@ pub fn diagnostics(&self) -> String {
         let crate_graph = self.crate_graph();
         for krate in crate_graph.iter().next() {
             let crate_def_map = self.crate_def_map(krate);
-            for (module_id, _) in crate_def_map.modules.iter() {
+            for module_id in crate_def_map.modules() {
                 let module_id = ModuleId { krate, module_id };
                 let module = crate::Module::from(module_id);
                 module.diagnostics(
diff --git a/crates/ra_hir_def/src/nameres.rs b/crates/ra_hir_def/src/nameres.rs
index 1331fbe3071..5fc59215008 100644
--- a/crates/ra_hir_def/src/nameres.rs
+++ b/crates/ra_hir_def/src/nameres.rs
@@ -87,7 +87,7 @@ pub struct CrateDefMap {
     prelude: Option<ModuleId>,
     extern_prelude: FxHashMap<Name, ModuleDefId>,
     root: CrateModuleId,
-    pub modules: Arena<CrateModuleId, ModuleData>,
+    modules: Arena<CrateModuleId, ModuleData>,
 
     /// Some macros are not well-behavior, which leads to infinite loop
     /// e.g. macro_rules! foo { ($ty:ty) => { foo!($ty); } }
@@ -259,6 +259,10 @@ pub fn resolve_path(
         (res.resolved_def, res.segment_index)
     }
 
+    pub fn modules(&self) -> impl Iterator<Item = CrateModuleId> + '_ {
+        self.modules.iter().map(|(id, _data)| id)
+    }
+
     pub fn modules_for_file(&self, file_id: FileId) -> impl Iterator<Item = CrateModuleId> + '_ {
         self.modules
             .iter()