diff --git a/lib/tests/packages-from-directory/c/not-a-namespace/not-a-package.nix b/lib/tests/packages-from-directory/c/not-a-namespace/not-a-package.nix
index e69de29bb2d1..ffcd4415b08f 100644
--- a/lib/tests/packages-from-directory/c/not-a-namespace/not-a-package.nix
+++ b/lib/tests/packages-from-directory/c/not-a-namespace/not-a-package.nix
@@ -0,0 +1 @@
+{ }
diff --git a/lib/tests/packages-from-directory/c/support-definitions.nix b/lib/tests/packages-from-directory/c/support-definitions.nix
index e69de29bb2d1..ffcd4415b08f 100644
--- a/lib/tests/packages-from-directory/c/support-definitions.nix
+++ b/lib/tests/packages-from-directory/c/support-definitions.nix
@@ -0,0 +1 @@
+{ }
diff --git a/pkgs/development/compilers/flutter/artifacts/prepare-artifacts.nix b/pkgs/development/compilers/flutter/artifacts/prepare-artifacts.nix
index 9309c6429828..def75e280da7 100644
--- a/pkgs/development/compilers/flutter/artifacts/prepare-artifacts.nix
+++ b/pkgs/development/compilers/flutter/artifacts/prepare-artifacts.nix
@@ -20,7 +20,7 @@
     runHook postInstall
   '';
 }).overrideAttrs (
-  if builtins.pathExists ./overrides/${src.flutterPlatform}.nix
-  then callPackage ./overrides/${src.flutterPlatform}.nix { }
+  if builtins.pathExists (./overrides + "/${src.flutterPlatform}.nix")
+  then callPackage (./overrides + "/${src.flutterPlatform}.nix") { }
   else ({ ... }: { })
 )
diff --git a/pkgs/development/compilers/flutter/update/get-artifact-hashes.nix b/pkgs/development/compilers/flutter/update/get-artifact-hashes.nix.in
similarity index 95%
rename from pkgs/development/compilers/flutter/update/get-artifact-hashes.nix
rename to pkgs/development/compilers/flutter/update/get-artifact-hashes.nix.in
index 89343a323165..069bcdb95718 100644
--- a/pkgs/development/compilers/flutter/update/get-artifact-hashes.nix
+++ b/pkgs/development/compilers/flutter/update/get-artifact-hashes.nix.in
@@ -35,7 +35,7 @@ let
                 flutter = flutterPackages."v${flutterCompactVersion}";
                 inherit flutterPlatform;
                 inherit systemPlatform;
-                hash = "";
+                hash = lib.fakeSha256;
               })
             systemPlatforms)
       ) [ ]
diff --git a/pkgs/development/compilers/flutter/update/get-dart-hashes.nix b/pkgs/development/compilers/flutter/update/get-dart-hashes.nix.in
similarity index 74%
rename from pkgs/development/compilers/flutter/update/get-dart-hashes.nix
rename to pkgs/development/compilers/flutter/update/get-dart-hashes.nix.in
index 4122110bccaa..f900c863195a 100644
--- a/pkgs/development/compilers/flutter/update/get-dart-hashes.nix
+++ b/pkgs/development/compilers/flutter/update/get-dart-hashes.nix.in
@@ -6,21 +6,21 @@ in
   x86_64-linux = { fetchzip }:
     fetchzip {
       url = "https://storage.googleapis.com/dart-archive/channels/stable/release/${dartVersion}/sdk/dartsdk-linux-x64-release.zip";
-      sha256 = "";
+      sha256 = "0000000000000000000000000000000000000000000000000000";
     };
   aarch64-linux = { fetchzip }:
     fetchzip {
       url = "https://storage.googleapis.com/dart-archive/channels/stable/release/${dartVersion}/sdk/dartsdk-linux-arm64-release.zip";
-      sha256 = "";
+      sha256 = "0000000000000000000000000000000000000000000000000000";
     };
   x86_64-darwin = { fetchzip }:
     fetchzip {
       url = "https://storage.googleapis.com/dart-archive/channels/stable/release/${dartVersion}/sdk/dartsdk-macos-x64-release.zip";
-      sha256 = "";
+      sha256 = "0000000000000000000000000000000000000000000000000000";
     };
   aarch64-darwin = { fetchzip }:
     fetchzip {
       url = "https://storage.googleapis.com/dart-archive/channels/stable/release/${dartVersion}/sdk/dartsdk-macos-arm64-release.zip";
-      sha256 = "";
+      sha256 = "0000000000000000000000000000000000000000000000000000";
     };
 }.${platform}
diff --git a/pkgs/development/compilers/flutter/update/get-flutter.nix b/pkgs/development/compilers/flutter/update/get-flutter.nix.in
similarity index 100%
rename from pkgs/development/compilers/flutter/update/get-flutter.nix
rename to pkgs/development/compilers/flutter/update/get-flutter.nix.in
diff --git a/pkgs/development/compilers/flutter/update/get-pubspec-lock.nix b/pkgs/development/compilers/flutter/update/get-pubspec-lock.nix.in
similarity index 100%
rename from pkgs/development/compilers/flutter/update/get-pubspec-lock.nix
rename to pkgs/development/compilers/flutter/update/get-pubspec-lock.nix.in
diff --git a/pkgs/development/compilers/flutter/update/update.py b/pkgs/development/compilers/flutter/update/update.py
index c622487cf9dc..618fae5468e5 100755
--- a/pkgs/development/compilers/flutter/update/update.py
+++ b/pkgs/development/compilers/flutter/update/update.py
@@ -23,7 +23,7 @@ NIXPKGS_ROOT = subprocess.Popen(['git',
 
 
 def load_code(name, **kwargs):
-    with open(f"{NIXPKGS_ROOT}/pkgs/development/compilers/flutter/update/{name}", 'r') as f:
+    with open(f"{NIXPKGS_ROOT}/pkgs/development/compilers/flutter/update/{name}.in", 'r') as f:
         code = f.read()
 
     for (key, value) in kwargs.items():