diff --git a/pkgs/tools/networking/openvpn/auth-ldap-fix-conftest.patch b/pkgs/tools/networking/openvpn/auth-ldap-fix-conftest.patch
new file mode 100644
index 000000000000..c571fda5d3c1
--- /dev/null
+++ b/pkgs/tools/networking/openvpn/auth-ldap-fix-conftest.patch
@@ -0,0 +1,36 @@
+diff --git a/aclocal.m4 b/aclocal.m4
+index e5b7dbf..01cecf1 100644
+--- a/aclocal.m4
++++ b/aclocal.m4
+@@ -73,6 +73,7 @@ AC_DEFUN([OD_OBJC_RUNTIME],[
+ 				AC_LANG_PROGRAM([
+ 						#include <objc/objc.h>
+ 						#include <objc/Object.h>
++						#include <stdio.h>
+ 					], [
+ 						Object *obj = @<:@Object alloc@:>@;
+ 						puts(@<:@obj name@:>@);
+@@ -94,6 +95,7 @@ AC_DEFUN([OD_OBJC_RUNTIME],[
+ 					AC_LANG_PROGRAM([
+ 							#include <objc/objc.h>
+ 							#include <objc/Object.h>
++							#include <stdio.h>
+ 						], [
+ 							Object *obj = @<:@Object alloc@:>@;
+ 							puts(@<:@obj name@:>@);
+@@ -131,6 +133,7 @@ AC_DEFUN([OD_OBJC_RUNTIME],[
+ 					AC_LANG_PROGRAM([
+ 							#include <objc/objc.h>
+ 							#include <objc/objc-api.h>
++							#include <stdio.h>
+ 						], [
+ 							id class = objc_lookUpClass("Object");
+ 							id obj = @<:@class alloc@:>@;
+@@ -162,6 +165,7 @@ AC_DEFUN([OD_OBJC_RUNTIME],[
+ 							#else
+ 							#include <objc/objc-api.h>
+ 							#endif
++							#include <stdio.h>
+ 						], [
+ 							#ifdef __GNU_LIBOBJC_
+ 							Class class = objc_lookUpClass("Object");
diff --git a/pkgs/tools/networking/openvpn/openvpn-auth-ldap.nix b/pkgs/tools/networking/openvpn/openvpn-auth-ldap.nix
index 70dacddafc37..df93dacb4711 100644
--- a/pkgs/tools/networking/openvpn/openvpn-auth-ldap.nix
+++ b/pkgs/tools/networking/openvpn/openvpn-auth-ldap.nix
@@ -20,6 +20,10 @@ stdenv.mkDerivation rec {
     sha256 = "1j30sygj8nm8wjqxzpb7pfzr3dxqxggswzxd7z5yk7y04c0yp1hb";
   };
 
+  patches = [
+    ./auth-ldap-fix-conftest.patch
+  ];
+
   nativeBuildInputs = [
     autoreconfHook
     gnustep.base