diff --git a/Makefile b/Makefile
index fe397e018..866c0961e 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,5 @@
 makefiles = \
+  mk/precompiled-headers.mk \
   local.mk \
   src/libutil/local.mk \
   src/libstore/local.mk \
diff --git a/mk/lib.mk b/mk/lib.mk
index b0a36cf8d..1da51d879 100644
--- a/mk/lib.mk
+++ b/mk/lib.mk
@@ -89,7 +89,6 @@ include mk/jars.mk
 include mk/patterns.mk
 include mk/templates.mk
 include mk/tests.mk
-include mk/precompiled-headers.mk
 
 
 # Include all sub-Makefiles.
diff --git a/perl/Makefile b/perl/Makefile
index 284c75022..7ddb0cf69 100644
--- a/perl/Makefile
+++ b/perl/Makefile
@@ -7,8 +7,9 @@ GLOBAL_CXXFLAGS += -g -Wall
 OPTIMIZE = 1
 
 ifeq ($(OPTIMIZE), 1)
-  GLOBAL_CFLAGS += -O3
   GLOBAL_CXXFLAGS += -O3
+else
+  GLOBAL_CXXFLAGS += -O0
 endif
 
 include mk/lib.mk
diff --git a/perl/configure.ac b/perl/configure.ac
index 966700695..c3769e142 100644
--- a/perl/configure.ac
+++ b/perl/configure.ac
@@ -6,7 +6,6 @@ CFLAGS=
 CXXFLAGS=
 AC_PROG_CC
 AC_PROG_CXX
-AX_CXX_COMPILE_STDCXX_11
 
 # Use 64-bit file system calls so that we can support files > 2 GiB.
 AC_SYS_LARGEFILE
@@ -69,14 +68,15 @@ AC_SUBST(perlFlags)
 
 PKG_CHECK_MODULES([NIX], [nix-store])
 
-NEED_PROG([NIX_INSTANTIATE_PROGRAM], [nix-instantiate])
+NEED_PROG([NIX], [nix])
 
 # Get nix configure values
-nixbindir=$("$NIX_INSTANTIATE_PROGRAM" --eval '<nix/config.nix>' -A nixBinDir | tr -d \")
-nixlibexecdir=$("$NIX_INSTANTIATE_PROGRAM" --eval '<nix/config.nix>' -A nixLibexecDir | tr -d \")
-nixlocalstatedir=$("$NIX_INSTANTIATE_PROGRAM" --eval '<nix/config.nix>' -A nixLocalstateDir | tr -d \")
-nixsysconfdir=$("$NIX_INSTANTIATE_PROGRAM" --eval '<nix/config.nix>' -A nixSysconfDir | tr -d \")
-nixstoredir=$("$NIX_INSTANTIATE_PROGRAM" --eval '<nix/config.nix>' -A nixStoreDir | tr -d \")
+export NIX_REMOTE=daemon
+nixbindir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixBinDir)
+nixlibexecdir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixLibexecDir)
+nixlocalstatedir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixLocalstateDir)
+nixsysconfdir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixSysconfDir)
+nixstoredir=$("$NIX" --experimental-features nix-command eval --raw -f '<nix/config.nix>' nixStoreDir)
 AC_SUBST(nixbindir)
 AC_SUBST(nixlibexecdir)
 AC_SUBST(nixlocalstatedir)
diff --git a/precompiled-headers.h b/precompiled-headers.h
index c5790bec4..e0d885b23 100644
--- a/precompiled-headers.h
+++ b/precompiled-headers.h
@@ -43,23 +43,13 @@
 #include <errno.h>
 #include <fcntl.h>
 #include <grp.h>
-#include <net/if.h>
 #include <netdb.h>
-#include <netinet/ip.h>
 #include <pwd.h>
-#include <sched.h>
 #include <signal.h>
-#include <sys/ioctl.h>
-#include <sys/mman.h>
-#include <sys/mount.h>
-#include <sys/param.h>
-#include <sys/personality.h>
 #include <sys/resource.h>
 #include <sys/select.h>
 #include <sys/socket.h>
-#include <sys/socket.h>
 #include <sys/stat.h>
-#include <sys/syscall.h>
 #include <sys/time.h>
 #include <sys/types.h>
 #include <sys/utsname.h>