diff --git a/crates/hir-ty/src/db.rs b/crates/hir-ty/src/db.rs
index dd5639f00d2..69283e55a4c 100644
--- a/crates/hir-ty/src/db.rs
+++ b/crates/hir-ty/src/db.rs
@@ -156,7 +156,7 @@ fn normalize_projection(
         &self,
         projection: crate::ProjectionTy,
         env: Arc<crate::TraitEnvironment>,
-    ) -> Option<crate::Ty>;
+    ) -> Ty;
 
     #[salsa::invoke(trait_solve_wait)]
     #[salsa::transparent]
diff --git a/crates/hir-ty/src/traits.rs b/crates/hir-ty/src/traits.rs
index aaff894b34f..372c3a3cca6 100644
--- a/crates/hir-ty/src/traits.rs
+++ b/crates/hir-ty/src/traits.rs
@@ -69,10 +69,10 @@ pub(crate) fn normalize_projection_query(
     db: &dyn HirDatabase,
     projection: ProjectionTy,
     env: Arc<TraitEnvironment>,
-) -> Option<Ty> {
-    let mut table = InferenceTable::new(db, env.clone());
+) -> Ty {
+    let mut table = InferenceTable::new(db, env);
     let ty = table.normalize_projection_ty(projection);
-    Some(table.resolve_completely(ty))
+    table.resolve_completely(ty)
 }
 
 /// Solve a trait goal using Chalk.
diff --git a/crates/hir/src/lib.rs b/crates/hir/src/lib.rs
index b5974a0cfc9..d2717c56654 100644
--- a/crates/hir/src/lib.rs
+++ b/crates/hir/src/lib.rs
@@ -2892,7 +2892,12 @@ pub fn normalize_trait_assoc_type(
             })
             .build();
 
-        db.normalize_projection(projection, self.env.clone()).map(|ty| self.derived(ty))
+        let ty = db.normalize_projection(projection, self.env.clone());
+        if ty.is_unknown() {
+            None
+        } else {
+            Some(self.derived(ty))
+        }
     }
 
     pub fn is_copy(&self, db: &dyn HirDatabase) -> bool {