diff --git a/pkgs/development/compilers/jwasm/default.nix b/pkgs/development/compilers/jwasm/default.nix
index fa004bca3117e..faaeae431e853 100644
--- a/pkgs/development/compilers/jwasm/default.nix
+++ b/pkgs/development/compilers/jwasm/default.nix
@@ -24,6 +24,10 @@ stdenv.mkDerivation (finalAttrs: {
       --replace "/usr/local/bin" "${placeholder "out"}/bin"
   '';
 
+  preInstall = ''
+    mkdir -p ${placeholder "out"}/bin
+  '';
+
   postInstall = ''
     install -Dpm644 $src/Html/License.html \
                     $src/Html/Manual.html \
@@ -35,6 +39,7 @@ stdenv.mkDerivation (finalAttrs: {
     homepage = "https://github.com/Baron-von-Riedesel/JWasm/";
     description = "A MASM-compatible x86 assembler";
     changelog = "https://github.com/Baron-von-Riedesel/JWasm/releases/tag/v${finalAttrs.version}";
+    mainProgram = "jwasm";
     license = licenses.gpl2Plus;
     maintainers = with maintainers; [ AndersonTorres ];
     platforms = platforms.unix;