diff --git a/Cargo.lock b/Cargo.lock
index 1a1af3dcb1..27e1808bb4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -4241,6 +4241,7 @@ name = "ty_ide"
 version = "0.0.0"
 dependencies = [
  "bitflags 2.9.3",
+ "camino",
  "get-size2",
  "insta",
  "itertools 0.14.0",
diff --git a/crates/ty_ide/Cargo.toml b/crates/ty_ide/Cargo.toml
index e00b8db200..08fbb7eedb 100644
--- a/crates/ty_ide/Cargo.toml
+++ b/crates/ty_ide/Cargo.toml
@@ -33,7 +33,7 @@ smallvec = { workspace = true }
 tracing = { workspace = true }
 
 [dev-dependencies]
-
+camino = { workspace = true }
 insta = { workspace = true, features = ["filters"] }
 
 [lints]
diff --git a/crates/ty_ide/src/lib.rs b/crates/ty_ide/src/lib.rs
index 6baea75a8f..b695ee5804 100644
--- a/crates/ty_ide/src/lib.rs
+++ b/crates/ty_ide/src/lib.rs
@@ -286,10 +286,12 @@ impl HasNavigationTargets for TypeDefinition<'_> {
 
 #[cfg(test)]
 mod tests {
+    use camino::Utf8Component;
     use insta::internals::SettingsBindDropGuard;
+
     use ruff_db::Db;
     use ruff_db::diagnostic::{Diagnostic, DiagnosticFormat, DisplayDiagnosticConfig};
-    use ruff_db::files::{File, system_path_to_file};
+    use ruff_db::files::{File, FileRootKind, system_path_to_file};
     use ruff_db::system::{DbWithWritableSystem, SystemPath, SystemPathBuf};
     use ruff_python_trivia::textwrap::dedent;
     use ruff_text_size::TextSize;
@@ -378,6 +380,19 @@ mod tests {
                 db.write_file(path, contents)
                     .expect("write to memory file system to be successful");
 
+                // Add a root for the top-most component.
+                let top = path.components().find_map(|c| match c {
+                    Utf8Component::Normal(c) => Some(c),
+                    _ => None,
+                });
+                if let Some(top) = top {
+                    let top = SystemPath::new(top);
+                    if db.system().is_directory(top) {
+                        db.files()
+                            .try_add_root(&db, top, FileRootKind::LibrarySearchPath);
+                    }
+                }
+
                 let file = system_path_to_file(&db, path).expect("newly written file to existing");
 
                 if let Some(offset) = cursor_offset {
diff --git a/crates/ty_python_semantic/src/module_resolver/module.rs b/crates/ty_python_semantic/src/module_resolver/module.rs
index 3586f52933..fdafa64323 100644
--- a/crates/ty_python_semantic/src/module_resolver/module.rs
+++ b/crates/ty_python_semantic/src/module_resolver/module.rs
@@ -161,9 +161,11 @@ fn all_submodule_names_for_package(db: &dyn Db, file: File) -> Option<Vec<Name>>
             // tree. When the revision gets bumped, the cache
             // that Salsa creates does for this routine will be
             // invalidated.
-            if let Some(root) = db.files().root(db, parent_directory) {
-                let _ = root.revision(db);
-            }
+            let root = db
+                .files()
+                .root(db, parent_directory)
+                .expect("System search path should have a registered root");
+            let _ = root.revision(db);
 
             db.system()
                 .read_directory(parent_directory)