diff --git a/pkgs/applications/networking/powerdns-admin/default.nix b/pkgs/applications/networking/powerdns-admin/default.nix
index 51a51b3fb1c7..cc31f25390a7 100644
--- a/pkgs/applications/networking/powerdns-admin/default.nix
+++ b/pkgs/applications/networking/powerdns-admin/default.nix
@@ -19,6 +19,7 @@ let
         src = oldAttrs.src.override {
           inherit version;
           hash = "sha256-yKhbKNN3zHc35G4tnytPRO48Dh3qxr9G3e/HGH0weXo=";
+          sha256 = "";
         };
 
         SETUPTOOLS_SCM_PRETEND_VERSION = version;
diff --git a/pkgs/build-support/fetchurl/default.nix b/pkgs/build-support/fetchurl/default.nix
index 7ec831c61ac7..a85d53adb829 100644
--- a/pkgs/build-support/fetchurl/default.nix
+++ b/pkgs/build-support/fetchurl/default.nix
@@ -117,6 +117,9 @@ let
     else throw "fetchurl requires either `url` or `urls` to be set";
 
   hash_ =
+    # Many other combinations don't make sense, but this is the most common one:
+    if hash != "" && sha256 != "" then throw "multiple hashes passed to fetchurl" else
+
     if hash != "" then { outputHashAlgo = null; outputHash = hash; }
     else if md5 != "" then throw "fetchurl does not support md5 anymore, please use sha256 or sha512"
     else if (outputHash != "" && outputHashAlgo != "") then { inherit outputHashAlgo outputHash; }
diff --git a/pkgs/servers/home-assistant/default.nix b/pkgs/servers/home-assistant/default.nix
index 6b0e704df52a..a23488798bbc 100644
--- a/pkgs/servers/home-assistant/default.nix
+++ b/pkgs/servers/home-assistant/default.nix
@@ -95,8 +95,9 @@ let
     (self: super: {
       pytest-aiohttp = super.pytest-aiohttp.overridePythonAttrs (oldAttrs: rec {
         version = "0.3.0";
-        src = oldAttrs.src.override {
+        src = self.fetchPypi {
           inherit version;
+          pname = "pytest-aiohttp";
           hash = "sha256-ySmFQzljeXc3WDhwO2L+9jUoWYvAqdRRY566lfSqpE8=";
         };
         propagatedBuildInputs = with python3.pkgs; [ aiohttp pytest ];
@@ -142,7 +143,16 @@ let
     })
 
     # Pinned due to API changes in 0.1.0
-    (mkOverride "poolsense" "0.0.8" "sha256-17MHrYRmqkH+1QLtgq2d6zaRtqvb9ju9dvPt9gB2xCc=")
+    (self: super: {
+      poolsense = super.poolsense.overridePythonAttrs (oldAttrs: rec {
+        version = "0.0.8";
+        src = super.fetchPypi {
+          pname = "poolsense";
+          inherit version;
+          hash = "sha256-17MHrYRmqkH+1QLtgq2d6zaRtqvb9ju9dvPt9gB2xCc=";
+        };
+      });
+    })
 
     # Pinned due to API changes >0.3.5.3
     (self: super: {
@@ -274,16 +284,6 @@ let
     })
   ];
 
-  mkOverride = attrName: version: hash:
-    self: super: {
-      ${attrName} = super.${attrName}.overridePythonAttrs (oldAttrs: {
-        inherit version;
-        src = oldAttrs.src.override {
-          inherit version hash;
-        };
-      });
-    };
-
   python = python3.override {
     # Put packageOverrides at the start so they are applied after defaultOverrides
     packageOverrides = lib.foldr lib.composeExtensions (self: super: { }) ([ packageOverrides ] ++ defaultOverrides);
diff --git a/pkgs/tools/admin/oci-cli/default.nix b/pkgs/tools/admin/oci-cli/default.nix
index 16d7a4ce9cb1..c1c6de5e5a75 100644
--- a/pkgs/tools/admin/oci-cli/default.nix
+++ b/pkgs/tools/admin/oci-cli/default.nix
@@ -13,6 +13,7 @@ let
         src = oldAttrs.src.override {
           inherit version;
           hash = "sha256-0rUlXHxjSbwb0eWeCM0SrLvWPOZJ8liHVXg6qU37axo=";
+          sha256 = "";
         };
       });
 
@@ -21,6 +22,7 @@ let
         src = oldAttrs.src.override {
           inherit version;
           sha256 = "b85d0567b8666149a93172712e68920734333c0ce7e89b78b3e987f71e5ed4f9";
+          hash = "";
         };
         doCheck = false;
       });
diff --git a/pkgs/tools/audio/tts/default.nix b/pkgs/tools/audio/tts/default.nix
index 159d68feac0f..6291c45f839e 100644
--- a/pkgs/tools/audio/tts/default.nix
+++ b/pkgs/tools/audio/tts/default.nix
@@ -21,7 +21,8 @@ let
       # TypeError: mel() takes 0 positional arguments but 2 positional arguments (and 3 keyword-only arguments) were given
       librosa = super.librosa.overridePythonAttrs (oldAttrs: rec {
         version = "0.8.1";
-        src = oldAttrs.src.override {
+        src = super.fetchPypi {
+          pname = "librosa";
           inherit version;
           sha256 = "c53d05e768ae4a3e553ae21c2e5015293e5efbfd5c12d497f1104cb519cca6b3";
         };
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 5a7c2839a65a..7d628281f78e 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -15475,6 +15475,7 @@ with pkgs;
     src = oldAttrs.src.override {
       inherit version;
       hash = "sha256-XzZuhRFZ2Pcs5o0yuMDt2lbuU3wB6faOyjgr0VEK9l0=";
+      sha256 = "";
     };
     meta.changelog = "https://github.com/ansible/ansible/blob/v${version}/changelogs/CHANGELOG-v${lib.versions.majorMinor version}.rst";
   }));