diff --git a/pkgs/development/python-modules/eventlet/default.nix b/pkgs/development/python-modules/eventlet/default.nix
index 92ff2cdacaf6..e8cb1971f2e5 100644
--- a/pkgs/development/python-modules/eventlet/default.nix
+++ b/pkgs/development/python-modules/eventlet/default.nix
@@ -29,7 +29,7 @@ buildPythonPackage rec {
 
   doCheck = !stdenv.isDarwin;
 
-  preCheck = ''
+  preCheck = lib.optionalString doCheck ''
     echo "nameserver 127.0.0.1" > resolv.conf
     export NIX_REDIRECTS=/etc/protocols=${iana-etc}/etc/protocols:/etc/resolv.conf=$(realpath resolv.conf)
     export LD_PRELOAD=${libredirect}/lib/libredirect.so
diff --git a/pkgs/development/python-modules/sentry-sdk/default.nix b/pkgs/development/python-modules/sentry-sdk/default.nix
index d7678941597e..b7349caa233f 100644
--- a/pkgs/development/python-modules/sentry-sdk/default.nix
+++ b/pkgs/development/python-modules/sentry-sdk/default.nix
@@ -47,7 +47,7 @@ buildPythonPackage rec {
   # `socket.getprotobyname('tcp')`, which reads from this file). Normally
   # this path isn't available in the sandbox. Therefore, use libredirect
   # to make on eavailable from `iana-etc`. This is a test-only operation.
-  preCheck = ''
+  preCheck = lib.optionalString doCheck ''
     export NIX_REDIRECTS=/etc/protocols=${iana-etc}/etc/protocols
     export LD_PRELOAD=${libredirect}/lib/libredirect.so
   '';