diff --git a/Modules/FindOpenSSL.cmake b/Modules/FindOpenSSL.cmake
index 6f80d8e62f..352c4cc1e3 100644
--- a/Modules/FindOpenSSL.cmake
+++ b/Modules/FindOpenSSL.cmake
@@ -104,6 +104,11 @@ The following variables may be set to control search behavior:
   .. versionadded:: 3.5
 
   Set to ``TRUE`` to choose the MT version of the lib.
+
+``ENV{PKG_CONFIG_PATH}``
+  On UNIX-like systems, ``pkg-config`` is used to locate the system OpenSSL.
+  Set the ``PKG_CONFIG_PATH`` environment varialbe to look in alternate
+  locations.  Useful on multi-lib systems.
 #]=======================================================================]
 
 macro(_OpenSSL_test_and_find_dependencies ssl_library crypto_library)