3 files changed, 12 insertions, 13 deletions
diff --git a/pkgs/servers/mail/archiveopteryx/default.nix b/pkgs/servers/mail/archiveopteryx/default.nix
index 3443a508aea4..55cc4c121f0f 100644
--- a/pkgs/servers/mail/archiveopteryx/default.nix
+++ b/pkgs/servers/mail/archiveopteryx/default.nix
@@ -21,7 +21,7 @@ stdenv.mkDerivation rec {
   '';
 
   # fix build on gcc7+
-  NIX_CFLAGS_COMPILE = [
+  NIX_CFLAGS_COMPILE = builtins.toString [
     "-Wno-error=builtin-declaration-mismatch"
     "-Wno-error=implicit-fallthrough"
     "-Wno-error=deprecated-copy"
diff --git a/pkgs/servers/mail/opensmtpd/extras.nix b/pkgs/servers/mail/opensmtpd/extras.nix
index f7ed6382a7be..14d36ad65549 100644
--- a/pkgs/servers/mail/opensmtpd/extras.nix
+++ b/pkgs/servers/mail/opensmtpd/extras.nix
@@ -48,39 +48,38 @@ stdenv.mkDerivation rec {
     "--with-scheduler-ram"
     "--with-scheduler-stub"
 
-  ] ++ stdenv.lib.optional enablePython [
+  ] ++ stdenv.lib.optionals enablePython [
     "--with-python=${python2}"
     "--with-filter-python"
     "--with-queue-python"
     "--with-table-python"
     "--with-scheduler-python"
 
-  ] ++ stdenv.lib.optional enableLua [
+  ] ++ stdenv.lib.optionals enableLua [
     "--with-lua=${pkgconfig}"
     "--with-filter-lua"
 
-  ] ++ stdenv.lib.optional enablePerl [
+  ] ++ stdenv.lib.optionals enablePerl [
     "--with-perl=${perl}"
     "--with-filter-perl"
 
-  ] ++ stdenv.lib.optional enableMysql [
+  ] ++ stdenv.lib.optionals enableMysql [
     "--with-table-mysql"
 
-  ] ++ stdenv.lib.optional enablePostgres [
+  ] ++ stdenv.lib.optionals enablePostgres [
     "--with-table-postgres"
 
-  ] ++ stdenv.lib.optional enableSqlite [
+  ] ++ stdenv.lib.optionals enableSqlite [
     "--with-table-sqlite"
 
-  ] ++ stdenv.lib.optional enableRedis [
+  ] ++ stdenv.lib.optionals enableRedis [
     "--with-table-redis"
   ];
 
-  NIX_CFLAGS_COMPILE =
-    stdenv.lib.optional enableRedis
+  NIX_CFLAGS_COMPILE = stdenv.lib.optionalString enableRedis
       "-I${hiredis}/include/hiredis -lhiredis"
-    ++ stdenv.lib.optional enableMysql
-      "-L${libmysqlclient}/lib/mysql";
+    + stdenv.lib.optionalString enableMysql
+      " -L${libmysqlclient}/lib/mysql";
 
   meta = with stdenv.lib; {
     homepage = https://www.opensmtpd.org/;
diff --git a/pkgs/servers/mail/postfix/default.nix b/pkgs/servers/mail/postfix/default.nix
index b3345f9420cb..c0e6252a5518 100644
--- a/pkgs/servers/mail/postfix/default.nix
+++ b/pkgs/servers/mail/postfix/default.nix
@@ -79,7 +79,7 @@ in stdenv.mkDerivation rec {
     make makefiles CCARGS='${ccargs}' AUXLIBS='${auxlibs}'
   '';
 
-  NIX_LDFLAGS = lib.optional withLDAP "-llber";
+  NIX_LDFLAGS = lib.optionalString withLDAP "-llber";
 
   installTargets = [ "non-interactive-package" ];