diff --git a/pkgs/development/libraries/vapoursynth/default.nix b/pkgs/development/libraries/vapoursynth/default.nix
index 7121b6fed02d2d..a68e713bb51f7c 100644
--- a/pkgs/development/libraries/vapoursynth/default.nix
+++ b/pkgs/development/libraries/vapoursynth/default.nix
@@ -12,13 +12,13 @@ with stdenv.lib;
 
 stdenv.mkDerivation rec {
   name = "vapoursynth-${version}";
-  version = "R45.1";
+  version = "R46";
 
   src = fetchFromGitHub {
     owner  = "vapoursynth";
     repo   = "vapoursynth";
     rev    = version;
-    sha256 = "09fj4k75cksx1imivqfyr945swlr8k392kkdgzldwc4404qv82s6";
+    sha256 = "1xbwva12l68awplardf47ydlx904wifw468npaxa9cx9dvd5mv13";
   };
 
   nativeBuildInputs = [ pkgconfig autoreconfHook nasm ];
diff --git a/pkgs/development/libraries/zimg/default.nix b/pkgs/development/libraries/zimg/default.nix
index 12fb076d946be3..d22292669fae90 100644
--- a/pkgs/development/libraries/zimg/default.nix
+++ b/pkgs/development/libraries/zimg/default.nix
@@ -1,18 +1,20 @@
 { stdenv, fetchFromGitHub, autoreconfHook }:
 
-stdenv.mkDerivation rec{
-  name = "zimg-${version}";
-  version = "2.8";
+stdenv.mkDerivation rec {
+  pname = "zimg";
+  version = "2.9.1";
 
   src = fetchFromGitHub {
     owner  = "sekrit-twc";
     repo   = "zimg";
     rev    = "release-${version}";
-    sha256 = "0s4n1swg1hgv81l8hvf0ny0fn305vf6l6dakbj452304p6ihxd83";
+    sha256 = "0q9migrxyp5wc6lcl6gnfs1zwn1ncqna6cm7vz3c993vvmgdf1p9";
   };
 
   nativeBuildInputs = [ autoreconfHook ];
 
+  enableParallelBuilding = true;
+
   meta = with stdenv.lib; {
     description = "Scaling, colorspace conversion and dithering library";
     homepage    = https://github.com/sekrit-twc/zimg;