diff --git a/pkgs/development/ocaml-modules/afl-persistent/default.nix b/pkgs/development/ocaml-modules/afl-persistent/default.nix
index 5625cd95764f..ba266ade830e 100644
--- a/pkgs/development/ocaml-modules/afl-persistent/default.nix
+++ b/pkgs/development/ocaml-modules/afl-persistent/default.nix
@@ -12,7 +12,7 @@ stdenv.mkDerivation rec {
     sha256 = "06yyds2vcwlfr2nd3gvyrazlijjcrd1abnvkfpkaadgwdw3qam1i";
   };
 
-  buildInputs = [ ocaml findlib ];
+  nativeBuildInputs = [ ocaml findlib ];
 
   # don't run tests in buildPhase
   # don't overwrite test binary
diff --git a/pkgs/development/ocaml-modules/lwt/default.nix b/pkgs/development/ocaml-modules/lwt/default.nix
index 7d6424564d2f..be15d2b72a54 100644
--- a/pkgs/development/ocaml-modules/lwt/default.nix
+++ b/pkgs/development/ocaml-modules/lwt/default.nix
@@ -17,9 +17,8 @@ buildDunePackage rec {
     sha256 = "0cq2qy23sa1a5zk6nja3c652mp29i84yfrkcwks6i8sdqwli36jy";
   };
 
-  nativeBuildInputs = [ pkg-config ];
-  buildInputs = [ cppo dune-configurator ]
-   ++ optional (!versionAtLeast ocaml.version "4.08") ocaml-syntax-shims
+  nativeBuildInputs = [ pkg-config cppo dune-configurator ];
+  buildInputs = optional (!versionAtLeast ocaml.version "4.08") ocaml-syntax-shims
    ++ optional (!versionAtLeast ocaml.version "4.07") ncurses;
   propagatedBuildInputs = [ libev mmap ocplib-endian seq result ];
 
diff --git a/pkgs/development/ocaml-modules/mrmime/default.nix b/pkgs/development/ocaml-modules/mrmime/default.nix
index 6d3663509bc1..a5c2a68ee47b 100644
--- a/pkgs/development/ocaml-modules/mrmime/default.nix
+++ b/pkgs/development/ocaml-modules/mrmime/default.nix
@@ -36,15 +36,6 @@ buildDunePackage rec {
 
   useDune2 = true;
 
-  buildInputs = [
-    afl-persistent
-    bigarray-compat
-    bigarray-overlap
-    bigstringaf
-    fpath
-    mirage-crypto-rng
-  ];
-
   propagatedBuildInputs = [
     angstrom
     base64
@@ -59,6 +50,12 @@ buildDunePackage rec {
     rresult
     unstrctrd
     uutf
+    afl-persistent
+    bigarray-compat
+    bigarray-overlap
+    bigstringaf
+    fpath
+    mirage-crypto-rng
   ];
 
   checkInputs = [
diff --git a/pkgs/development/ocaml-modules/ocplib-endian/default.nix b/pkgs/development/ocaml-modules/ocplib-endian/default.nix
index 2cb066a7c035..f2cf4acbf27b 100644
--- a/pkgs/development/ocaml-modules/ocplib-endian/default.nix
+++ b/pkgs/development/ocaml-modules/ocplib-endian/default.nix
@@ -11,7 +11,7 @@ buildDunePackage rec {
 
   useDune2 = true;
 
-  buildInputs = [ cppo ];
+  nativeBuildInputs = [ cppo ];
 
   meta = with lib; {
     description = "Optimised functions to read and write int16/32/64";