diff --git a/pkgs/build-support/ocaml/default.nix b/pkgs/build-support/ocaml/default.nix
index cc2001c66e2e..3957b955a2c6 100644
--- a/pkgs/build-support/ocaml/default.nix
+++ b/pkgs/build-support/ocaml/default.nix
@@ -23,7 +23,7 @@ stdenv.mkDerivation (args // {
 
   setupHook = if setupHook == null && hasSharedObjects
   then writeText "setupHook.sh" ''
-    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
+    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
     ''
   else setupHook;
 
diff --git a/pkgs/development/compilers/reason/default.nix b/pkgs/development/compilers/reason/default.nix
index 5d7d0ce6684b..20286dcc43c9 100644
--- a/pkgs/development/compilers/reason/default.nix
+++ b/pkgs/development/compilers/reason/default.nix
@@ -27,8 +27,8 @@ stdenv.mkDerivation rec {
   postInstall = ''
     wrapProgram $out/bin/rtop \
       --prefix PATH : "${utop}/bin" \
-      --set CAML_LD_LIBRARY_PATH ${ocaml_lwt}/lib/ocaml/${ocaml.version}/site-lib:$CAML_LD_LIBRARY_PATH \
-      --set OCAMLPATH $out/lib/ocaml/${ocaml.version}/site-lib:$OCAMLPATH
+      --prefix CAML_LD_LIBRARY_PATH : "${ocaml_lwt}/lib/ocaml/${ocaml.version}/site-lib" \
+      --prefix OCAMLPATH : "$out/lib/ocaml/${ocaml.version}/site-lib"
   '';
 
   meta = with stdenv.lib; {
diff --git a/pkgs/development/ocaml-modules/bap/default.nix b/pkgs/development/ocaml-modules/bap/default.nix
index 0766e6e8a8c5..a988582ce6ce 100644
--- a/pkgs/development/ocaml-modules/bap/default.nix
+++ b/pkgs/development/ocaml-modules/bap/default.nix
@@ -28,8 +28,8 @@ stdenv.mkDerivation rec {
   createFindlibDestdir = true;
 
   setupHook = writeText "setupHook.sh" ''
-    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
-    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}-llvm-plugins/"
+    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
+    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}-llvm-plugins/"
   '';
 
   nativeBuildInputs = [ which makeWrapper ];
@@ -44,7 +44,7 @@ stdenv.mkDerivation rec {
   installPhase = ''
     export OCAMLPATH=$OCAMLPATH:$OCAMLFIND_DESTDIR;
     export PATH=$PATH:$out/bin
-    export CAML_LD_LIBRARY_PATH=$CAML_LD_LIBRARY_PATH:$OCAMLFIND_DESTDIR/bap-plugin-llvm/:$OCAMLFIND_DESTDIR/bap/
+    export CAML_LD_LIBRARY_PATH=''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}$OCAMLFIND_DESTDIR/bap-plugin-llvm/:$OCAMLFIND_DESTDIR/bap/
     mkdir -p $out/lib/bap
     make install
     rm $out/bin/baptop
diff --git a/pkgs/development/ocaml-modules/ocsigen-server/default.nix b/pkgs/development/ocaml-modules/ocsigen-server/default.nix
index 426fecf39155..9b0b8c433c2c 100644
--- a/pkgs/development/ocaml-modules/ocsigen-server/default.nix
+++ b/pkgs/development/ocaml-modules/ocsigen-server/default.nix
@@ -41,7 +41,7 @@ stdenv.mkDerivation rec {
   ''
   rm -rf $out/var/run
   wrapProgram $out/bin/ocsigenserver \
-    --prefix CAML_LD_LIBRARY_PATH : "$CAML_LD_LIBRARY_PATH:${mkpath ssl "ssl"}:${mkpath ocamlnet "netsys"}:${mkpath ocamlnet "netstring"}:${mkpath ocaml_pcre "pcre"}:${mkpath ocaml_sqlite3 "sqlite3"}"
+    --suffix CAML_LD_LIBRARY_PATH : "${mkpath ssl "ssl"}:${mkpath ocamlnet "netsys"}:${mkpath ocamlnet "netstring"}:${mkpath ocaml_pcre "pcre"}:${mkpath ocaml_sqlite3 "sqlite3"}"
   '';
 
   dontPatchShebangs = true;
diff --git a/pkgs/development/tools/ocaml/camlidl/default.nix b/pkgs/development/tools/ocaml/camlidl/default.nix
index 09de5b02737b..309c44d6d463 100644
--- a/pkgs/development/tools/ocaml/camlidl/default.nix
+++ b/pkgs/development/tools/ocaml/camlidl/default.nix
@@ -37,7 +37,7 @@ stdenv.mkDerivation rec {
   '';
 
   setupHook = writeText "setupHook.sh" ''
-    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
+    export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/${name}/"
     export NIX_CFLAGS_COMPILE+=" -isystem $1/lib/ocaml/${ocaml.version}/site-lib/camlidl"
     export NIX_LDFLAGS+=" -L $1/lib/ocaml/${ocaml.version}/site-lib/camlidl"
   '';
diff --git a/pkgs/development/tools/ocaml/findlib/default.nix b/pkgs/development/tools/ocaml/findlib/default.nix
index 6bf34a6e9587..9db5ed10c842 100644
--- a/pkgs/development/tools/ocaml/findlib/default.nix
+++ b/pkgs/development/tools/ocaml/findlib/default.nix
@@ -35,7 +35,7 @@ stdenv.mkDerivation rec {
             export OCAMLPATH="''${OCAMLPATH-}''${OCAMLPATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/"
         fi
         if test -d "''$1/lib/ocaml/${ocaml.version}/site-lib/stublibs"; then
-            export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/stublibs"
+            export CAML_LD_LIBRARY_PATH="''${CAML_LD_LIBRARY_PATH-}''${CAML_LD_LIBRARY_PATH:+:}''$1/lib/ocaml/${ocaml.version}/site-lib/stublibs"
         fi
         export OCAMLFIND_DESTDIR="''$out/lib/ocaml/${ocaml.version}/site-lib/"
         if test -n "''${createFindlibDestdir-}"; then
diff --git a/pkgs/development/tools/ocaml/utop/default.nix b/pkgs/development/tools/ocaml/utop/default.nix
index 290ab9b571f4..f154b94ae336 100644
--- a/pkgs/development/tools/ocaml/utop/default.nix
+++ b/pkgs/development/tools/ocaml/utop/default.nix
@@ -39,6 +39,7 @@ stdenv.mkDerivation rec {
        installPhase = ''
          mkdir -p "$out"/${path}
          for e in OCAMLPATH CAML_LD_LIBRARY_PATH; do
+           [[ -v "$e" ]] || continue
            printf %s "''${!e}" > "$out"/${path}/$e
          done
        '';