diff --git a/pkgs/development/compilers/gnat-bootstrap/default.nix b/pkgs/development/compilers/gnat-bootstrap/default.nix
index d59a6b4f51fbd..bbf1173f1b001 100644
--- a/pkgs/development/compilers/gnat-bootstrap/default.nix
+++ b/pkgs/development/compilers/gnat-bootstrap/default.nix
@@ -54,16 +54,13 @@ in {
 
   nativeBuildInputs = [
     dejagnu
-    expat
     gmp
     guile
     libipt
     mpfr
-    ncurses5
     python3
     readline
     sourceHighlight
-    xz
     zlib
   ] ++ lib.optionals stdenv.buildPlatform.isLinux [
     autoPatchelfHook
@@ -72,6 +69,14 @@ in {
     elfutils
   ];
 
+  buildInputs = [
+    expat
+    ncurses5
+    xz
+  ];
+
+  strictDeps = true;
+
   postPatch = lib.optionalString (stdenv.hostPlatform.isDarwin) ''
     substituteInPlace lib/gcc/${upstreamTriplet}/${gccVersion}/install-tools/mkheaders.conf \
       --replace "SYSTEM_HEADER_DIR=\"/usr/include\"" "SYSTEM_HEADER_DIR=\"/include\""