diff --git a/configure.in b/configure.in
index b9692c8..28364c3 100644
--- a/configure.in
+++ b/configure.in
@@ -13,6 +13,7 @@ AC_CHECK_PROG([YACC], [bison -y], [bison -y], [:])
 AC_PATH_PROG([NSCD], [nscd], [/usr/sbin/nscd],
 	     [$PATH$PATH_SEPARATOR/usr/sbin$PATH_SEPARATOR/sbin])
 AC_ARG_VAR([NSCD], [Path to nscd])
+AC_USE_SYSTEM_EXTENSIONS
 
 LT_INIT([disable-static])
 
@@ -115,7 +116,7 @@ AC_TYPE_MODE_T
 AC_TYPE_OFF_T
 AC_TYPE_SIZE_T
 
-AC_CHECK_FUNCS_ONCE([__secure_getenv])
+AC_CHECK_FUNCS([__secure_getenv secure_getenv])
 
 # Modify CFLAGS after all tests are run (some of them could fail because
 # of the -Werror).
diff --git a/lib/config.c b/lib/config.c
index 1b30f97..29e7120 100644
--- a/lib/config.c
+++ b/lib/config.c
@@ -40,8 +40,12 @@
  * from the libuser configuration.
  */
 
-#ifdef HAVE___SECURE_GETENV
-#define getenv(string) __secure_getenv(string)
+#if defined(HAVE_SECURE_GETENV)
+#  define safe_getenv(string) secure_getenv(string)
+#elif defined(HAVE___SECURE_GETENV)
+#  define safe_getenv(string) __secure_getenv(string)
+#else
+#  error Neither secure_getenv not __secure_getenv are available
 #endif
 
 struct config_config {
@@ -266,7 +270,7 @@ lu_cfg_init(struct lu_context *context, struct lu_error **error)
 	if ((getuid() == geteuid()) && (getgid() == getegid())) {
 		const char *t;
 
-		t = getenv("LIBUSER_CONF");
+		t = safe_getenv("LIBUSER_CONF");
 		if (t != NULL)
 			filename = t;
 	}