diff --git a/pkgs/tools/security/fcrackzip/default.nix b/pkgs/tools/security/fcrackzip/default.nix
index b3b82a015115..6a60878c88d7 100644
--- a/pkgs/tools/security/fcrackzip/default.nix
+++ b/pkgs/tools/security/fcrackzip/default.nix
@@ -8,6 +8,8 @@ stdenv.mkDerivation rec {
     sha256 = "0l1qsk949vnz18k4vjf3ppq8p497966x4c7f2yx18x8pk35whn2a";
   };
 
+  CFLAGS = "-std=gnu89";
+
   # 'fcrackzip --use-unzip' cannot deal with file names containing a single quote
   # https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=430387
   patches = [ ./fcrackzip_forkexec.patch ];