diff --git a/pkgs/development/python-modules/indexed-bzip2/default.nix b/pkgs/development/python-modules/indexed-bzip2/default.nix
index 53788b566e52..d15e075e5d57 100644
--- a/pkgs/development/python-modules/indexed-bzip2/default.nix
+++ b/pkgs/development/python-modules/indexed-bzip2/default.nix
@@ -1,13 +1,15 @@
 { lib
 , buildPythonPackage
+, cython
 , fetchPypi
 , pythonOlder
+, setuptools
 }:
 
 buildPythonPackage rec {
   pname = "indexed_bzip2";
   version = "1.6.0";
-  format = "setuptools";
+  pyproject = true;
 
   disabled = pythonOlder "3.6";
 
@@ -16,6 +18,8 @@ buildPythonPackage rec {
     hash = "sha256-3HUiigZR91/nbOAMOuSHGcPtqkkEaj3VepyMhmKOHpI=";
   };
 
+  nativeBuildInputs = [ cython setuptools ];
+
   # has no tests
   doCheck = false;
 
@@ -27,6 +31,5 @@ buildPythonPackage rec {
     homepage = "https://github.com/mxmlnkn/indexed_bzip2";
     license = licenses.mit; # dual MIT and asl20, https://internals.rust-lang.org/t/rationale-of-apache-dual-licensing/8952
     maintainers = with lib.maintainers; [ mxmlnkn ];
-    platforms = platforms.all;
   };
 }
diff --git a/pkgs/development/python-modules/indexed-gzip/default.nix b/pkgs/development/python-modules/indexed-gzip/default.nix
index 7b0bf177bf19..bfe9e894ce5f 100644
--- a/pkgs/development/python-modules/indexed-gzip/default.nix
+++ b/pkgs/development/python-modules/indexed-gzip/default.nix
@@ -2,6 +2,7 @@
 , buildPythonPackage
 , fetchPypi
 , pythonOlder
+, setuptools
 , cython
 , zlib
 }:
@@ -9,7 +10,7 @@
 buildPythonPackage rec {
   pname = "indexed_gzip";
   version = "1.8.7";
-  format = "setuptools";
+  pyproject = true;
 
   disabled = pythonOlder "3.7";
 
@@ -18,7 +19,7 @@ buildPythonPackage rec {
     hash = "sha256-dryq1LLC+lVHj/i+m60ubGGItlX5/clCnwNGrexI92I=";
   };
 
-  nativeBuildInputs = [ cython ];
+  nativeBuildInputs = [ cython setuptools ];
 
   buildInputs = [ zlib ];
 
@@ -32,6 +33,5 @@ buildPythonPackage rec {
     homepage = "https://github.com/pauldmccarthy/indexed_gzip";
     license = licenses.zlib;
     maintainers = with lib.maintainers; [ mxmlnkn ];
-    platforms = platforms.all;
   };
 }
diff --git a/pkgs/development/python-modules/indexed-zstd/default.nix b/pkgs/development/python-modules/indexed-zstd/default.nix
index f9d643c8ff49..88cb6f05930a 100644
--- a/pkgs/development/python-modules/indexed-zstd/default.nix
+++ b/pkgs/development/python-modules/indexed-zstd/default.nix
@@ -2,6 +2,7 @@
 , buildPythonPackage
 , fetchPypi
 , pythonOlder
+, setuptools
 , cython
 , zstd
 }:
@@ -9,7 +10,7 @@
 buildPythonPackage rec {
   pname = "indexed_zstd";
   version = "1.6.0";
-  format = "setuptools";
+  pyproject = true;
 
   disabled = pythonOlder "3.6";
 
@@ -18,10 +19,12 @@ buildPythonPackage rec {
     hash = "sha256-icCerrv6ihBjSTS4Fsw7qhoA5ha8yegfMVRiIOhTvvY=";
   };
 
-  nativeBuildInputs = [ cython ];
+  nativeBuildInputs = [ cython setuptools ];
 
   buildInputs = [ zstd.dev ];
 
+  postPatch = "cython -3 --cplus indexed_zstd/indexed_zstd.pyx";
+
   # has no tests
   doCheck = false;
 
@@ -32,6 +35,5 @@ buildPythonPackage rec {
     homepage = "https://github.com/martinellimarco/indexed_zstd";
     license = licenses.mit;
     maintainers = with lib.maintainers; [ mxmlnkn ];
-    platforms = platforms.all;
   };
 }
diff --git a/pkgs/development/python-modules/rapidgzip/default.nix b/pkgs/development/python-modules/rapidgzip/default.nix
index f50537524cbf..79bddb9dba74 100644
--- a/pkgs/development/python-modules/rapidgzip/default.nix
+++ b/pkgs/development/python-modules/rapidgzip/default.nix
@@ -1,14 +1,16 @@
 { lib
 , buildPythonPackage
+, cython
 , fetchPypi
 , pythonOlder
+, setuptools
 , nasm
 }:
 
 buildPythonPackage rec {
   pname = "rapidgzip";
   version = "0.13.0";
-  format = "setuptools";
+  pyproject = true;
 
   disabled = pythonOlder "3.6";
 
@@ -17,7 +19,7 @@ buildPythonPackage rec {
     hash = "sha256-MwT4+wzlNXfDLT/o/oT1iy9cVlFIIXc18r7dg+x5SXY=";
   };
 
-  nativeBuildInputs = [ nasm ];
+  nativeBuildInputs = [ cython nasm setuptools ];
 
   # has no tests
   doCheck = false;
@@ -31,6 +33,5 @@ buildPythonPackage rec {
     changelog = "https://github.com/mxmlnkn/rapidgzip/blob/rapidgzip-v${version}/python/rapidgzip/CHANGELOG.md";
     license = licenses.mit; # dual MIT and asl20, https://internals.rust-lang.org/t/rationale-of-apache-dual-licensing/8952
     maintainers = with lib.maintainers; [ mxmlnkn ];
-    platforms = platforms.all;
   };
 }
diff --git a/pkgs/development/python-modules/ratarmountcore/default.nix b/pkgs/development/python-modules/ratarmountcore/default.nix
index 90a45cecdb7a..844fa2c49923 100644
--- a/pkgs/development/python-modules/ratarmountcore/default.nix
+++ b/pkgs/development/python-modules/ratarmountcore/default.nix
@@ -1,12 +1,13 @@
 { lib
 , buildPythonPackage
-, fetchgit
+, fetchFromGitHub
 , pythonOlder
 , pytestCheckHook
 , indexed-bzip2
 , indexed-gzip
 , indexed-zstd
 , python-xz
+, setuptools
 , rapidgzip
 , rarfile
 , zstandard     # Python bindings
@@ -15,35 +16,42 @@
 
 buildPythonPackage rec {
   pname = "ratarmountcore";
-  version = "0.6.0";
-  format = "setuptools";
+  version = "0.6.3";
+  pyproject = true;
 
   disabled = pythonOlder "3.6";
 
-  src = fetchgit {
-    url = "https://github.com/mxmlnkn/ratarmount";
-    # The revision is hardcoded for now to fix problems with the tests, which are not worthy of a new release
-    # tag because releases do not officially contain tests. On the next release, use the commented revision,
-    # which points to a release tag, instead.
-    #rev = "core-v${version}";
-    rev = "ea43572dfbac4770a27ef2169f72ff73ee4a4ae9";
-    hash = "sha256-sPApM5OW+UbujFXHSL4ptMaegajz7FNtXz/KftTlw+U=";
+  src = fetchFromGitHub {
+    owner = "mxmlnkn";
+    repo = "ratarmount";
+    rev = "core-v${version}";
+    hash = "sha256-2jG066BUkhyHRqRyFAucQRJrjXQNw2ccCxERKkltO3Y=";
     fetchSubmodules = true;
   };
 
   sourceRoot = "${src.name}/core";
 
+  nativeBuildInputs = [ setuptools ];
   propagatedBuildInputs = [ indexed-gzip indexed-bzip2 indexed-zstd python-xz rapidgzip rarfile ];
 
   pythonImportsCheck = [ "ratarmountcore" ];
 
   nativeCheckInputs = [ pytestCheckHook zstandard zstd ];
 
+  disabledTestPaths = [
+    # Disable this test because for arcane reasons running pytest with nix-build uses 10-100x
+    # more virtual memory than running the test directly or inside a local development nix-shell.
+    # This virtual memory usage caused os.fork called by Python multiprocessing to fail with
+    # "OSError: [Errno 12] Cannot allocate memory" on a test system with 16 GB RAM. It worked fine
+    # on a system with 96 GB RAM. In order to avoid build errors on "low"-memory systems, this
+    # test is disabled for now.
+    "tests/test_BlockParallelReaders.py"
+  ];
+
   meta = with lib; {
     description = "Library for accessing archives by way of indexing";
     homepage = "https://github.com/mxmlnkn/ratarmount/tree/master/core";
     license = licenses.mit;
     maintainers = with lib.maintainers; [ mxmlnkn ];
-    platforms = platforms.all;
   };
 }