diff --git a/tools/FindPythonLibsNew.cmake b/tools/FindPythonLibsNew.cmake
index 9948f07ac9..b1d9441723 100644
--- a/tools/FindPythonLibsNew.cmake
+++ b/tools/FindPythonLibsNew.cmake
@@ -200,14 +200,15 @@ if(PYBIND11_PYTHONLIBS_OVERWRITE OR NOT DEFINED PYTHON_MODULE_DEBUG_POSTFIX)
 endif()
 if(PYBIND11_PYTHONLIBS_OVERWRITE OR NOT DEFINED PYTHON_MODULE_EXTENSION)
   get_filename_component(PYTHON_MODULE_EXTENSION "${_PYTHON_MODULE_EXT_SUFFIX}" EXT)
-  if (NOT "$ENV{SETUPTOOLS_EXT_SUFFIX}" STREQUAL ""
-      AND NOT "$ENV{SETUPTOOLS_EXT_SUFFIX}" STREQUAL "${PYTHON_MODULE_EXTENSION}")
-    message(AUTHOR_WARNING,
-            "SETUPTOOLS_EXT_SUFFIX is set to \"$ENV{SETUPTOOLS_EXT_SUFFIX}\", "
-            "but the auto-calculated Python extension suffix is \"${PYTHON_MODULE_EXTENSION}\". "
-            "This may cause problems when importing the Python extensions. "
-            "If you are using cross-compiling Python, you may need to "
-            "set PYTHON_MODULE_EXTENSION manually.")
+  if(NOT "$ENV{SETUPTOOLS_EXT_SUFFIX}" STREQUAL "" AND NOT "$ENV{SETUPTOOLS_EXT_SUFFIX}" STREQUAL
+                                                       "${PYTHON_MODULE_EXTENSION}")
+    message(
+      AUTHOR_WARNING,
+      "SETUPTOOLS_EXT_SUFFIX is set to \"$ENV{SETUPTOOLS_EXT_SUFFIX}\", "
+      "but the auto-calculated Python extension suffix is \"${PYTHON_MODULE_EXTENSION}\". "
+      "This may cause problems when importing the Python extensions. "
+      "If you are using cross-compiling Python, you may need to "
+      "set PYTHON_MODULE_EXTENSION manually.")
   endif()
 endif()