diff --git a/pyproject.toml b/pyproject.toml
index 6aaab1d3..a909dd7b 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -1,6 +1,6 @@
 [build-system]
 requires = [
-  "setuptools", "wheel", "scikit-build", "cmake", "pip",
+  "setuptools", "wheel", "scikit-build", "cmake", "pip==21.3.1",
   "numpy==1.13.3; python_version=='3.6' and platform_machine != 'aarch64' and platform_machine != 'arm64'",
   "numpy==1.14.5; python_version=='3.7' and platform_machine != 'aarch64' and platform_machine != 'arm64'",
   "numpy==1.17.3; python_version=='3.8' and platform_machine != 'aarch64' and platform_machine != 'arm64'",