diff --git a/pkgs/applications/science/logic/picosat/default.nix b/pkgs/applications/science/logic/picosat/default.nix
index e026cfad218..cd672ed00e7 100644
--- a/pkgs/applications/science/logic/picosat/default.nix
+++ b/pkgs/applications/science/logic/picosat/default.nix
@@ -9,6 +9,10 @@ stdenv.mkDerivation rec {
     sha256 = "0m578rpa5rdn08d10kr4lbsdwp4402hpavrz6n7n53xs517rn5hm";
   };
 
+  prePatch = ''
+    substituteInPlace picosat.c --replace "sys/unistd.h" "unistd.h"
+  '';
+
   configurePhase = "./configure.sh --shared --trace";
 
   installPhase = ''