diff --git a/pkgs/servers/mail/exim/default.nix b/pkgs/servers/mail/exim/default.nix
index 1a911668a540..710a018e3adb 100644
--- a/pkgs/servers/mail/exim/default.nix
+++ b/pkgs/servers/mail/exim/default.nix
@@ -122,6 +122,7 @@ stdenv.mkDerivation rec {
     homepage = "https://exim.org/";
     description = "A mail transfer agent (MTA)";
     license = with licenses; [ gpl2Plus bsd3 ];
+    mainProgram = "exim";
     platforms = platforms.linux;
     maintainers = with maintainers; [ tv ajs124 das_j ];
     changelog = "https://github.com/Exim/exim/blob/exim-${version}/doc/doc-txt/ChangeLog";