diff --git a/pkgs/tools/misc/memtest86+/default.nix b/pkgs/tools/misc/memtest86+/default.nix
index dbd5a46e10a..7e382426336 100644
--- a/pkgs/tools/misc/memtest86+/default.nix
+++ b/pkgs/tools/misc/memtest86+/default.nix
@@ -20,7 +20,7 @@ stdenv.mkDerivation rec {
     fi
   '';
 
-  NIX_CFLAGS_COMPILE = "-I.";
+  NIX_CFLAGS_COMPILE = "-I. -std=gnu90";
 
   buildFlags = "memtest.bin";