diff --git a/pkgs/development/libraries/x265/default.nix b/pkgs/development/libraries/x265/default.nix
index ae3392aeb12..48ed6cf4680 100644
--- a/pkgs/development/libraries/x265/default.nix
+++ b/pkgs/development/libraries/x265/default.nix
@@ -84,9 +84,11 @@ stdenv.mkDerivation rec {
     "-DENABLE_SHARED=ON"
     "-DHIGH_BIT_DEPTH=OFF"
     "-DENABLE_HDR10_PLUS=OFF"
+  ] ++ stdenv.lib.optionals is64bit [
     "-DEXTRA_LIB=${libx265-10}/lib/libx265.a;${libx265-12}/lib/libx265.a"
     "-DLINKED_10BIT=ON"
     "-DLINKED_12BIT=ON"
+  ] ++ [
     (mkFlag cliSupport "ENABLE_CLI")
   ] ++ cmakeFlagsAll;