diff --git a/pkgs/development/libraries/libiscsi/default.nix b/pkgs/development/libraries/libiscsi/default.nix
index 806a9729c574c..826593b9d66c6 100644
--- a/pkgs/development/libraries/libiscsi/default.nix
+++ b/pkgs/development/libraries/libiscsi/default.nix
@@ -11,6 +11,11 @@ stdenv.mkDerivation rec {
     sha256 = "0ajrkkg5awmi8m4b3mha7h07ylg18k252qprvk1sgq0qbyd66zy7";
   };
 
+  postPatch = ''
+    substituteInPlace lib/socket.c \
+      --replace "void iscsi_decrement_iface_rr() {" "void iscsi_decrement_iface_rr(void) {"
+  '';
+
   nativeBuildInputs = [ autoreconfHook ];
 
   # This problem is gone on libiscsi master.