diff --git a/default.nix b/default.nix
index 7c1cf54..51d5a62 100644
--- a/default.nix
+++ b/default.nix
@@ -26,7 +26,7 @@ self: super: rec {
         pname = "starlette";
           version = "0.19.0";
           format = "setuptools";
-          src = fetchFromGitHub {
+          src = pkgs.fetchFromGitHub {
             owner = "encode";
             repo = pname;
             rev = version;
@@ -69,7 +69,7 @@ self: super: rec {
         pname = "fastapi";
           version = "0.75.2";
           format = "flit";
-          src = fetchFromGitHub {
+          src = pkgs.fetchFromGitHub {
             owner = "tiangolo";
             repo = pname;
             rev = version;
@@ -97,7 +97,7 @@ self: super: rec {
 
           patches = [
             # Bump starlette, https://github.com/tiangolo/fastapi/pull/4483
-            (fetchpatch {
+            (pkgs.fetchpatch {
               name = "support-later-starlette.patch";
               # PR contains multiple commits
               url = "https://patch-diff.githubusercontent.com/raw/tiangolo/fastapi/pull/4483.patch";