diff --git a/pkgs/development/libraries/openldap/default.nix b/pkgs/development/libraries/openldap/default.nix
index a4274f064e5..56955b88ee4 100644
--- a/pkgs/development/libraries/openldap/default.nix
+++ b/pkgs/development/libraries/openldap/default.nix
@@ -40,8 +40,8 @@ stdenv.mkDerivation rec {
     ++ stdenv.lib.optional stdenv.isFreeBSD "--with-pic";
 
   postBuild = ''
-    make $makeFlags -C contrib/slapd-modules/passwd/sha2
-    make $makeFlags -C contrib/slapd-modules/passwd/pbkdf2
+    make $makeFlags CC=$CC -C contrib/slapd-modules/passwd/sha2
+    make $makeFlags CC=$CC -C contrib/slapd-modules/passwd/pbkdf2
   '';
 
   doCheck = false; # needs a running LDAP server
diff --git a/pkgs/tools/system/efibootmgr/default.nix b/pkgs/tools/system/efibootmgr/default.nix
index 3323ac24897..dd898de0fc2 100644
--- a/pkgs/tools/system/efibootmgr/default.nix
+++ b/pkgs/tools/system/efibootmgr/default.nix
@@ -25,7 +25,7 @@ stdenv.mkDerivation rec {
   # We have no LTO here since commit 22284b07.
   postPatch = if stdenv.isi686 then "sed '/^CFLAGS/s/-flto//' -i Make.defaults" else null;
 
-  makeFlags = [ "EFIDIR=nixos" ];
+  makeFlags = [ "EFIDIR=nixos" "PKG_CONFIG=${stdenv.cc.targetPrefix}pkg-config" ];
 
   installFlags = [ "prefix=$(out)" ];