diff --git a/CMakeModules/UseCompat.cmake b/CMakeModules/UseCompat.cmake
index 7e624d9..7d7a338 100644
--- a/CMakeModules/UseCompat.cmake
+++ b/CMakeModules/UseCompat.cmake
@@ -1,24 +1,55 @@
+# - Use compat library providing various functions and macros that may be missing on some systems
+# Once done this will define
+#
+# compatsrc - sources to add to compilation
+#
+# Additionally, "compat.h" include directory is added and can be included.
+#
+# Author Michal Vasko <mvasko@cesnet.cz>
+#  Copyright (c) 2021 CESNET, z.s.p.o.
+#
+# This source code is licensed under BSD 3-Clause License (the "License").
+# You may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     https://opensource.org/licenses/BSD-3-Clause
+#
 include(CheckSymbolExists)
+include(CheckFunctionExists)
+include(CheckIncludeFile)
 include(TestBigEndian)
+if(POLICY CMP0075)
+    cmake_policy(SET CMP0075 NEW)
+endif()
 
-# defines "compatsrc" with source(s) of this small library
 macro(USE_COMPAT)
     # compatibility checks
     set(CMAKE_REQUIRED_DEFINITIONS -D_POSIX_C_SOURCE=200809L)
     list(APPEND CMAKE_REQUIRED_DEFINITIONS -D_GNU_SOURCE)
     list(APPEND CMAKE_REQUIRED_DEFINITIONS -D__BSD_VISIBLE=1)
+    set(CMAKE_REQUIRED_LIBRARIES pthread)
+
     check_symbol_exists(vdprintf "stdio.h;stdarg.h" HAVE_VDPRINTF)
     check_symbol_exists(asprintf "stdio.h" HAVE_ASPRINTF)
     check_symbol_exists(vasprintf "stdio.h" HAVE_VASPRINTF)
+    check_symbol_exists(getline "stdio.h" HAVE_GETLINE)
 
     check_symbol_exists(strndup "string.h" HAVE_STRNDUP)
     check_symbol_exists(strnstr "string.h" HAVE_STRNSTR)
-    check_symbol_exists(getline "stdio.h" HAVE_GETLINE)
+    check_symbol_exists(strdupa "string.h" HAVE_STRDUPA)
+    check_symbol_exists(strchrnul "string.h" HAVE_STRCHRNUL)
 
     check_symbol_exists(get_current_dir_name "unistd.h" HAVE_GET_CURRENT_DIR_NAME)
 
+    check_function_exists(pthread_mutex_timedlock HAVE_PTHREAD_MUTEX_TIMEDLOCK)
+
     TEST_BIG_ENDIAN(IS_BIG_ENDIAN)
 
+    check_include_file("stdatomic.h" HAVE_STDATOMIC)
+
+    unset(CMAKE_REQUIRED_DEFINITIONS)
+    unset(CMAKE_REQUIRED_LIBRARIES)
+
     # header and source file (adding the source directly allows for hiding its symbols)
     configure_file(${PROJECT_SOURCE_DIR}/compat/compat.h.in ${PROJECT_BINARY_DIR}/compat/compat.h @ONLY)
     include_directories(${PROJECT_BINARY_DIR}/compat)