diff --git a/pkgs/development/compilers/smlnj/bootstrap.nix b/pkgs/development/compilers/smlnj/bootstrap.nix
index aacebd48e9e..6aba529a8fc 100644
--- a/pkgs/development/compilers/smlnj/bootstrap.nix
+++ b/pkgs/development/compilers/smlnj/bootstrap.nix
@@ -44,5 +44,6 @@ stdenv.mkDerivation rec {
     license     = lib.licenses.free;
     platforms   = lib.platforms.darwin;
     maintainers = [ lib.maintainers.jwiegley ];
+    mainProgram = "sml";
   };
 }
diff --git a/pkgs/development/compilers/smlnj/default.nix b/pkgs/development/compilers/smlnj/default.nix
index d6d50f0303f..7f131157989 100644
--- a/pkgs/development/compilers/smlnj/default.nix
+++ b/pkgs/development/compilers/smlnj/default.nix
@@ -87,5 +87,6 @@ in stdenv.mkDerivation {
     license     = licenses.bsd3;
     platforms   = [ "x86_64-linux" "i686-linux" "x86_64-darwin" ];
     maintainers = with maintainers; [ thoughtpolice ];
+    mainProgram = "sml";
   };
 }