diff --git a/local.mk b/local.mk
index 7e3c77a65..408a82327 100644
--- a/local.mk
+++ b/local.mk
@@ -5,6 +5,11 @@ ERROR_SWITCH_ENUM = -Werror=switch-enum
 $(foreach i, config.h $(wildcard src/lib*/*.hh), \
   $(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))
 
+ifdef HOST_UNIX
+  $(foreach i, $(wildcard src/lib*/unix/*.hh), \
+    $(eval $(call install-file-in, $(i), $(includedir)/nix, 0644)))
+endif
+
 $(GCH): src/libutil/util.hh config.h
 
 GCH_CXXFLAGS = $(INCLUDE_libutil)
diff --git a/src/libcmd/local.mk b/src/libcmd/local.mk
index 7a7c46ee2..9aa33a9d3 100644
--- a/src/libcmd/local.mk
+++ b/src/libcmd/local.mk
@@ -6,7 +6,7 @@ libcmd_DIR := $(d)
 
 libcmd_SOURCES := $(wildcard $(d)/*.cc)
 
-libcmd_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) $(INCLUDE_libexpr) -I src/libmain
+libcmd_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) $(INCLUDE_libexpr) $(INCLUDE_libmain)
 
 libcmd_LDFLAGS = $(EDITLINE_LIBS) $(LOWDOWN_LIBS) $(THREAD_LDFLAGS)
 
diff --git a/src/libexpr/local.mk b/src/libexpr/local.mk
index 17f793ec3..ecadc5e5d 100644
--- a/src/libexpr/local.mk
+++ b/src/libexpr/local.mk
@@ -15,7 +15,7 @@ libexpr_SOURCES := \
 
 INCLUDE_libexpr := -I $(d)
 
-libexpr_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) -I src/libmain $(INCLUDE_libexpr)
+libexpr_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) $(INCLUDE_libmain) $(INCLUDE_libexpr)
 
 libexpr_LIBS = libutil libstore libfetchers
 
diff --git a/src/libfetchers/local.mk b/src/libfetchers/local.mk
index e229a0993..0fef1466b 100644
--- a/src/libfetchers/local.mk
+++ b/src/libfetchers/local.mk
@@ -5,10 +5,16 @@ libfetchers_NAME = libnixfetchers
 libfetchers_DIR := $(d)
 
 libfetchers_SOURCES := $(wildcard $(d)/*.cc)
+ifdef HOST_UNIX
+  libfetchers_SOURCES += $(wildcard $(d)/unix/*.cc)
+endif
 
 # Not just for this library itself, but also for downstream libraries using this library
 
 INCLUDE_libfetchers := -I $(d)
+ifdef HOST_UNIX
+  INCLUDE_libfetchers += -I $(d)/unix
+endif
 
 libfetchers_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers)
 
diff --git a/src/libmain/local.mk b/src/libmain/local.mk
index fde28a820..d41c49dd7 100644
--- a/src/libmain/local.mk
+++ b/src/libmain/local.mk
@@ -5,8 +5,13 @@ libmain_NAME = libnixmain
 libmain_DIR := $(d)
 
 libmain_SOURCES := $(wildcard $(d)/*.cc)
+ifdef HOST_UNIX
+  libmain_SOURCES += $(wildcard $(d)/unix/*.cc)
+endif
 
-libmain_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore)
+INCLUDE_libmain := -I $(d)
+
+libmain_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libmain)
 
 libmain_LDFLAGS += $(OPENSSL_LIBS)
 
diff --git a/src/libstore/local.mk b/src/libstore/local.mk
index 7eaa317e5..ccb7aeee2 100644
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@@ -5,6 +5,9 @@ libstore_NAME = libnixstore
 libstore_DIR := $(d)
 
 libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc $(d)/build/*.cc)
+ifdef HOST_UNIX
+  libstore_SOURCES += $(wildcard $(d)/unix/*.cc)
+endif
 
 libstore_LIBS = libutil
 
@@ -30,6 +33,9 @@ endif
 # Not just for this library itself, but also for downstream libraries using this library
 
 INCLUDE_libstore := -I $(d) -I $(d)/build
+ifdef HOST_UNIX
+  INCLUDE_libstore += -I $(d)/unix
+endif
 
 libstore_CXXFLAGS += \
  $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libstore) \
diff --git a/src/libutil/local.mk b/src/libutil/local.mk
index 4ffb6bd9d..9773ef64f 100644
--- a/src/libutil/local.mk
+++ b/src/libutil/local.mk
@@ -5,10 +5,22 @@ libutil_NAME = libnixutil
 libutil_DIR := $(d)
 
 libutil_SOURCES := $(wildcard $(d)/*.cc $(d)/signature/*.cc)
+ifdef HOST_UNIX
+  libutil_SOURCES += $(wildcard $(d)/unix/*.cc)
+endif
+ifdef HOST_LINUX
+    libutil_SOURCES += $(wildcard $(d)/linux/*.cc)
+endif
 
 # Not just for this library itself, but also for downstream libraries using this library
 
 INCLUDE_libutil := -I $(d)
+ifdef HOST_UNIX
+  INCLUDE_libutil += -I $(d)/unix
+endif
+ifdef HOST_LINUX
+  INCLUDE_libutil += -I $(d)/linux
+endif
 libutil_CXXFLAGS += $(INCLUDE_libutil)
 
 libutil_LDFLAGS += $(THREAD_LDFLAGS) $(LIBCURL_LIBS) $(SODIUM_LIBS) $(OPENSSL_LIBS) $(LIBBROTLI_LIBS) $(LIBARCHIVE_LIBS) $(BOOST_LDFLAGS) -lboost_context
diff --git a/src/nix/local.mk b/src/nix/local.mk
index 55544b564..9f6f31b3a 100644
--- a/src/nix/local.mk
+++ b/src/nix/local.mk
@@ -12,9 +12,19 @@ nix_SOURCES := \
   $(wildcard src/nix-daemon/*.cc) \
   $(wildcard src/nix-env/*.cc) \
   $(wildcard src/nix-instantiate/*.cc) \
-  $(wildcard src/nix-store/*.cc) \
+  $(wildcard src/nix-store/*.cc)
 
-nix_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) $(INCLUDE_libexpr) -I src/libmain -I src/libcmd -I doc/manual
+ifdef HOST_UNIX
+nix_SOURCES += \
+  $(wildcard $(d)/unix/*.cc)
+endif
+
+INCLUDE_nix := -I $(d)
+ifdef HOST_UNIX
+  INCLUDE_nix += -I $(d)/unix
+endif
+
+nix_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libfetchers) $(INCLUDE_libexpr) $(INCLUDE_libmain) -I src/libcmd -I doc/manual $(INCLUDE_nix)
 
 nix_LIBS = libexpr libmain libfetchers libstore libutil libcmd
 
diff --git a/src/resolve-system-dependencies/local.mk b/src/resolve-system-dependencies/local.mk
index f28fdab3b..e138c4080 100644
--- a/src/resolve-system-dependencies/local.mk
+++ b/src/resolve-system-dependencies/local.mk
@@ -6,7 +6,7 @@ resolve-system-dependencies_DIR := $(d)
 
 resolve-system-dependencies_INSTALL_DIR := $(libexecdir)/nix
 
-resolve-system-dependencies_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) -I src/libmain
+resolve-system-dependencies_CXXFLAGS += $(INCLUDE_libutil) $(INCLUDE_libstore) $(INCLUDE_libmain)
 
 resolve-system-dependencies_LIBS := libstore libmain libutil