diff --git a/pkgs/development/python-modules/astropy/default.nix b/pkgs/development/python-modules/astropy/default.nix
index 639e234acbb0..94376d603d5e 100644
--- a/pkgs/development/python-modules/astropy/default.nix
+++ b/pkgs/development/python-modules/astropy/default.nix
@@ -143,10 +143,6 @@ buildPythonPackage rec {
 
   preCheck = ''
     export HOME="$(mktemp -d)"
-    export OMP_NUM_THREADS=$(( $NIX_BUILD_CORES / 4 ))
-    if [ $OMP_NUM_THREADS -eq 0 ]; then
-      export OMP_NUM_THREADS=1
-    fi
 
     # See https://github.com/astropy/astropy/issues/17649 and see
     # --hypothesis-profile=ci pytest flag below.
diff --git a/pkgs/development/python-modules/captum/default.nix b/pkgs/development/python-modules/captum/default.nix
index 455eac5c5fc1..858e9abc4110 100644
--- a/pkgs/development/python-modules/captum/default.nix
+++ b/pkgs/development/python-modules/captum/default.nix
@@ -52,10 +52,6 @@ buildPythonPackage rec {
     scikit-learn
   ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=1
-  '';
-
   disabledTestPaths =
     lib.optionals stdenv.hostPlatform.isDarwin [
       # These tests may fail if multiple builds run them at the same time due
diff --git a/pkgs/development/python-modules/geometric/default.nix b/pkgs/development/python-modules/geometric/default.nix
index ec1553e164ab..08301b669d5c 100644
--- a/pkgs/development/python-modules/geometric/default.nix
+++ b/pkgs/development/python-modules/geometric/default.nix
@@ -28,10 +28,6 @@ buildPythonPackage rec {
     six
   ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=2
-  '';
-
   nativeCheckInputs = [ pytestCheckHook ];
 
   meta = {
diff --git a/pkgs/development/python-modules/imread/default.nix b/pkgs/development/python-modules/imread/default.nix
index a26b89fb2b02..bc0934f5bd7c 100644
--- a/pkgs/development/python-modules/imread/default.nix
+++ b/pkgs/development/python-modules/imread/default.nix
@@ -49,7 +49,6 @@ buildPythonPackage rec {
   preCheck = ''
     cd $TMPDIR
     export HOME=$TMPDIR
-    export OMP_NUM_THREADS=1
   '';
 
   meta = {
diff --git a/pkgs/development/python-modules/linearmodels/default.nix b/pkgs/development/python-modules/linearmodels/default.nix
index d67690e48774..9a5ae03ffe5f 100644
--- a/pkgs/development/python-modules/linearmodels/default.nix
+++ b/pkgs/development/python-modules/linearmodels/default.nix
@@ -67,8 +67,6 @@ buildPythonPackage (finalAttrs: {
 
   preCheck = ''
     rm linearmodels/__init__.py
-
-    export OMP_NUM_THREADS=1
   '';
 
   disabledTestPaths = [
diff --git a/pkgs/development/python-modules/mace-torch/default.nix b/pkgs/development/python-modules/mace-torch/default.nix
index 4ed39d479782..3c8b486f643b 100644
--- a/pkgs/development/python-modules/mace-torch/default.nix
+++ b/pkgs/development/python-modules/mace-torch/default.nix
@@ -82,10 +82,6 @@ buildPythonPackage (finalAttrs: {
     writableTmpDirAsHomeHook
   ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=1
-  '';
-
   disabledTests = [
     # _pickle.PickleError: ScriptFunction cannot be pickled
     "test_run_eval_fail_with_wrong_model"
diff --git a/pkgs/development/python-modules/numpy/1.nix b/pkgs/development/python-modules/numpy/1.nix
index 4fc274257916..7167ff94637e 100644
--- a/pkgs/development/python-modules/numpy/1.nix
+++ b/pkgs/development/python-modules/numpy/1.nix
@@ -18,6 +18,8 @@
   blas,
   lapack,
 
+  openmpCheckPhaseHook,
+
   # Reverse dependency
   sage,
 
@@ -93,7 +95,6 @@ buildPythonPackage (finalAttrs: {
   # see https://github.com/OpenMathLib/OpenBLAS/issues/2993
   preConfigure = ''
     sed -i 's/-faltivec//' numpy/distutils/system_info.py
-    export OMP_NUM_THREADS=$((NIX_BUILD_CORES > 64 ? 64 : NIX_BUILD_CORES))
   '';
 
   preBuild = ''
@@ -110,6 +111,10 @@ buildPythonPackage (finalAttrs: {
     typing-extensions
   ];
 
+  propagatedNativeBuildInputs = [
+    openmpCheckPhaseHook
+  ];
+
   preCheck = ''
     cd "$out"
   '';
diff --git a/pkgs/development/python-modules/numpy/2.nix b/pkgs/development/python-modules/numpy/2.nix
index c62619db4422..712130d6a0a8 100644
--- a/pkgs/development/python-modules/numpy/2.nix
+++ b/pkgs/development/python-modules/numpy/2.nix
@@ -93,10 +93,6 @@ buildPythonPackage (finalAttrs: {
   ]
   ++ lib.optionals (!stdenv.buildPlatform.canExecute stdenv.hostPlatform) [ mesonEmulatorHook ];
 
-  preConfigure = ''
-    export OMP_NUM_THREADS=$((NIX_BUILD_CORES > 64 ? 64 : NIX_BUILD_CORES))
-  '';
-
   buildInputs = [
     blas
     lapack
diff --git a/pkgs/development/python-modules/pyscf/default.nix b/pkgs/development/python-modules/pyscf/default.nix
index a248a1bb0d49..012d23f0dcfb 100644
--- a/pkgs/development/python-modules/pyscf/default.nix
+++ b/pkgs/development/python-modules/pyscf/default.nix
@@ -80,7 +80,6 @@ buildPythonPackage (finalAttrs: {
   preCheck = ''
     # Set config used by tests to ensure reproducibility
     echo 'pbc_tools_pbc_fft_engine = "NUMPY"' > pyscf/pyscf_config.py
-    export OMP_NUM_THREADS=1
     ulimit -s 20000
     export PYSCF_CONFIG_FILE=$(pwd)/pyscf/pyscf_config.py
   '';
diff --git a/pkgs/development/python-modules/qutip/default.nix b/pkgs/development/python-modules/qutip/default.nix
index 89e77b995785..aa968f51180d 100644
--- a/pkgs/development/python-modules/qutip/default.nix
+++ b/pkgs/development/python-modules/qutip/default.nix
@@ -62,7 +62,6 @@ buildPythonPackage (finalAttrs: {
   # This is due to the Cython-compiled modules not being in the correct location
   # of the source tree.
   preCheck = ''
-    export OMP_NUM_THREADS=$NIX_BUILD_CORES
     mkdir -p test && cd test
   '';
 
diff --git a/pkgs/development/python-modules/scikit-bio/default.nix b/pkgs/development/python-modules/scikit-bio/default.nix
index c909d8d66d08..1190d875005a 100644
--- a/pkgs/development/python-modules/scikit-bio/default.nix
+++ b/pkgs/development/python-modules/scikit-bio/default.nix
@@ -62,10 +62,6 @@ buildPythonPackage (finalAttrs: {
     pytestCheckHook
   ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=1
-  '';
-
   # only the $out dir contains the built cython extensions, so we run the tests inside there
   enabledTestPaths = [ "${placeholder "out"}/${python.sitePackages}/skbio" ];
 
diff --git a/pkgs/development/python-modules/scikit-learn/default.nix b/pkgs/development/python-modules/scikit-learn/default.nix
index b48f5a5d8f72..bf50ab0b7a63 100644
--- a/pkgs/development/python-modules/scikit-learn/default.nix
+++ b/pkgs/development/python-modules/scikit-learn/default.nix
@@ -116,7 +116,6 @@ buildPythonPackage rec {
   preCheck = ''
     cd $TMPDIR
     export HOME=$TMPDIR
-    export OMP_NUM_THREADS=1
   '';
 
   pythonImportsCheck = [ "sklearn" ];
diff --git a/pkgs/development/python-modules/scipy/default.nix b/pkgs/development/python-modules/scipy/default.nix
index 914b8ce07842..785a917fcf0d 100644
--- a/pkgs/development/python-modules/scipy/default.nix
+++ b/pkgs/development/python-modules/scipy/default.nix
@@ -175,11 +175,6 @@ buildPythonPackage (finalAttrs: {
   '';
 
   preCheck = ''
-    export OMP_NUM_THREADS=$(( $NIX_BUILD_CORES / 4 ))
-    if [ $OMP_NUM_THREADS -eq 0 ]; then
-      export OMP_NUM_THREADS=1
-    fi
-
     cd $out
   '';
 
diff --git a/pkgs/development/python-modules/torch-geometric/default.nix b/pkgs/development/python-modules/torch-geometric/default.nix
index 839f5c8e02e5..06863712e7c5 100644
--- a/pkgs/development/python-modules/torch-geometric/default.nix
+++ b/pkgs/development/python-modules/torch-geometric/default.nix
@@ -185,10 +185,6 @@ buildPythonPackage (finalAttrs: {
     writableTmpDirAsHomeHook
   ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=1
-  '';
-
   pytestFlags = [
     # DeprecationWarning: Failing to pass a value to the 'type_params' parameter of
     # 'typing._eval_type' is deprecated, as it leads to incorrect behaviour when calling
diff --git a/pkgs/development/python-modules/x-transformers/default.nix b/pkgs/development/python-modules/x-transformers/default.nix
index 1496775f5eec..16d3dff4fd61 100644
--- a/pkgs/development/python-modules/x-transformers/default.nix
+++ b/pkgs/development/python-modules/x-transformers/default.nix
@@ -42,10 +42,6 @@ buildPythonPackage (finalAttrs: {
 
   nativeCheckInputs = [ pytestCheckHook ];
 
-  preCheck = ''
-    export OMP_NUM_THREADS=1
-  '';
-
   # RuntimeError: torch.compile is not supported on Python 3.14+
   disabledTests = lib.optionals (pythonAtLeast "3.14") [ "test_up" ];