diff --git a/sample_environments.nix b/sample_environments.nix
index 554838a..390c733 100644
--- a/sample_environments.nix
+++ b/sample_environments.nix
@@ -21,7 +21,6 @@
   go = import ./sample_environments/go.nix args;
   octave = import ./sample_environments/octave.nix args;
   postgres = import ./sample_environments/postgres.nix args;
-  pypy3 = import ./sample_environments/pypy3.nix args;
   r = import ./sample_environments/r.nix args;
   r-ark = import ./sample_environments/r-ark.nix args;
   ruby_3_3 = import ./sample_environments/ruby_3_3.nix args;
@@ -42,4 +41,8 @@
   python312 = import ./sample_environments/python312.nix args;
   python313 = import ./sample_environments/python313.nix args;
   python3 = import ./sample_environments/python3.nix args;
+} // pkgsStable.lib.optionalAttrs pkgsStable.stdenv.targetPlatform.isLinux {
+  # PyPy's bootstrap interpreter doesn't build on Darwin: its libffi calls are guarded by
+  # -Wunguarded-availability-new against a deployment target older than macOS 10.15.
+  pypy3 = import ./sample_environments/pypy3.nix args;
 }
diff --git a/tests/app/Spec/Tests/Python.hs b/tests/app/Spec/Tests/Python.hs
index d23cea0..a27d1b0 100644
--- a/tests/app/Spec/Tests/Python.hs
+++ b/tests/app/Spec/Tests/Python.hs
@@ -3,9 +3,11 @@
 
 module Spec.Tests.Python (tests) where
 
+import Control.Monad (when)
 import Data.String.Interpolate
 import Data.Text
 import Language.LSP.Protocol.Types
+import System.Info (os)
 import Test.Sandwich as Sandwich
 import TestLib.JupyterRunnerContext
 import TestLib.LSP
@@ -26,7 +28,8 @@ tests = describe "Python" $ parallel $ do
   tests' ("python3", "python313")
   -- tests' ("python3", "python314")
 
-  pypyTests
+  -- PyPy's bootstrap interpreter doesn't build on Darwin, so there's no kernel to test there.
+  when (os /= "darwin") pypyTests
 
 tests' :: (Text, Text) -> LanguageSpec
 tests' (kernelName, pythonPackage) = introduceNixEnvironment [kernelSpec kernelName pythonPackage] [] [i|Python (#{pythonPackage})|] $ introduceJupyterRunner $ do
@@ -76,10 +79,12 @@ tests' (kernelName, pythonPackage) = introduceNixEnvironment [kernelSpec kernelN
 -- rather than the package and language server stack the CPython tests exercise.
 pypyTests :: LanguageSpec
 pypyTests = introduceNixEnvironment [pypyKernelSpec] [] "Python (pypy3)" $ introduceJupyterRunner $ do
+  -- The Nix attribute is kernels.pypy3, but the kernel it installs is named python3, the
+  -- same as the CPython ones.
   testHasExpectedFields "pypy3"
 
-  testKernelStdout "pypy3" [i|print("hi")|] "hi\n"
-  testKernelStdout "pypy3" [i|import platform; print(platform.python_implementation())|] "PyPy\n"
+  testKernelStdout "python3" [i|print("hi")|] "hi\n"
+  testKernelStdout "python3" [i|import platform; print(platform.python_implementation())|] "PyPy\n"
 
 pypyKernelSpec :: NixKernelSpec
 pypyKernelSpec = NixKernelSpec {