diff --git a/Makefile.config.in b/Makefile.config.in
index 7e3b35b98..588669f0a 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 AR = @AR@
 BDW_GC_LIBS = @BDW_GC_LIBS@
 BUILD_SHARED_LIBS = @BUILD_SHARED_LIBS@
diff --git a/misc/launchd/local.mk b/misc/launchd/local.mk
index 0ba722efb..a39188fe6 100644
--- a/misc/launchd/local.mk
+++ b/misc/launchd/local.mk
@@ -1,4 +1,4 @@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
 
   $(eval $(call install-data-in, $(d)/org.nixos.nix-daemon.plist, $(prefix)/Library/LaunchDaemons))
 
diff --git a/misc/systemd/local.mk b/misc/systemd/local.mk
index 004549fd2..7b8d0b4b8 100644
--- a/misc/systemd/local.mk
+++ b/misc/systemd/local.mk
@@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 
   $(foreach n, nix-daemon.socket nix-daemon.service, $(eval $(call install-file-in, $(d)/$(n), $(prefix)/lib/systemd/system, 0644)))
 
diff --git a/misc/upstart/local.mk b/misc/upstart/local.mk
index a73dc061e..b08e05fe2 100644
--- a/misc/upstart/local.mk
+++ b/misc/upstart/local.mk
@@ -1,4 +1,4 @@
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
 
   $(foreach n, nix-daemon.conf, $(eval $(call install-file-in, $(d)/$(n), $(sysconfdir)/init, 0644)))
 
diff --git a/mk/lib.mk b/mk/lib.mk
index 1da51d879..064d37629 100644
--- a/mk/lib.mk
+++ b/mk/lib.mk
@@ -11,8 +11,25 @@ noinst-scripts :=
 man-pages :=
 install-tests :=
 dist-files :=
-OS = $(shell uname -s)
 
+ifdef HOST_OS
+  HOST_KERNEL = $(firstword $(subst -, ,$(HOST_OS)))
+  ifeq ($(HOST_KERNEL), cygwin)
+    HOST_CYGWIN = 1
+  endif
+  ifeq ($(patsubst darwin%,,$(HOST_KERNEL)),)
+    HOST_DARWIN = 1
+  endif
+  ifeq ($(patsubst freebsd%,,$(HOST_KERNEL)),)
+    HOST_FREEBSD = 1
+  endif
+  ifeq ($(HOST_KERNEL), linux)
+    HOST_LINUX = 1
+  endif
+  ifeq ($(patsubst solaris%,,$(HOST_KERNEL)),)
+    HOST_SOLARIS = 1
+  endif
+endif
 
 # Hack to define a literal space.
 space :=
@@ -52,16 +69,16 @@ endif
 BUILD_SHARED_LIBS ?= 1
 
 ifeq ($(BUILD_SHARED_LIBS), 1)
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     GLOBAL_CFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
     GLOBAL_CXXFLAGS += -U__STRICT_ANSI__ -D_GNU_SOURCE
   else
     GLOBAL_CFLAGS += -fPIC
     GLOBAL_CXXFLAGS += -fPIC
   endif
-  ifneq ($(OS), Darwin)
-   ifneq ($(OS), SunOS)
-    ifneq ($(OS), FreeBSD)
+  ifndef HOST_DARWIN
+   ifndef HOST_SOLARIS
+    ifndef HOST_FREEBSD
      GLOBAL_LDFLAGS += -Wl,--no-copy-dt-needed-entries
     endif
    endif
diff --git a/mk/libraries.mk b/mk/libraries.mk
index 307e29b9d..b8a518853 100644
--- a/mk/libraries.mk
+++ b/mk/libraries.mk
@@ -1,9 +1,9 @@
 libs-list :=
 
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
   SO_EXT = dylib
 else
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     SO_EXT = dll
   else
     SO_EXT = so
@@ -59,7 +59,7 @@ define build-library
   $(1)_OBJS := $$(addprefix $(buildprefix), $$(addsuffix .o, $$(basename $$(_srcs))))
   _libs := $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_PATH))
 
-  ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+  ifdef HOST_CYGWIN
     $(1)_INSTALL_DIR ?= $$(bindir)
   else
     $(1)_INSTALL_DIR ?= $$(libdir)
@@ -73,18 +73,18 @@ define build-library
   ifeq ($(BUILD_SHARED_LIBS), 1)
 
     ifdef $(1)_ALLOW_UNDEFINED
-      ifeq ($(OS), Darwin)
+      ifdef HOST_DARWIN
         $(1)_LDFLAGS += -undefined suppress -flat_namespace
       endif
     else
-      ifneq ($(OS), Darwin)
-        ifneq (CYGWIN,$(findstring CYGWIN,$(OS)))
+      ifndef HOST_DARWIN
+        ifndef HOST_CYGWIN
           $(1)_LDFLAGS += -Wl,-z,defs
         endif
       endif
     endif
 
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       $(1)_LDFLAGS += -Wl,-soname=$$($(1)_NAME).$(SO_EXT)
     endif
 
@@ -93,7 +93,7 @@ define build-library
     $$($(1)_PATH): $$($(1)_OBJS) $$(_libs) | $$(_d)/
 	$$(trace-ld) $(CXX) -o $$(abspath $$@) -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE)) $$($(1)_LDFLAGS_UNINSTALLED)
 
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       $(1)_LDFLAGS_USE += -Wl,-rpath,$$(abspath $$(_d))
     endif
     $(1)_LDFLAGS_USE += -L$$(_d) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
@@ -108,7 +108,7 @@ define build-library
 	$$(trace-ld) $(CXX) -o $$@ -shared $$(LDFLAGS) $$(GLOBAL_LDFLAGS) $$($(1)_OBJS) $$($(1)_LDFLAGS) $$($(1)_LDFLAGS_PROPAGATED) $$(foreach lib, $$($(1)_LIBS), $$($$(lib)_LDFLAGS_USE_INSTALLED))
 
     $(1)_LDFLAGS_USE_INSTALLED += -L$$(DESTDIR)$$($(1)_INSTALL_DIR) -l$$(patsubst lib%,%,$$(strip $$($(1)_NAME)))
-    ifneq ($(OS), Darwin)
+    ifndef HOST_DARWIN
       ifeq ($(SET_RPATH_TO_LIBS), 1)
         $(1)_LDFLAGS_USE_INSTALLED += -Wl,-rpath,$$($(1)_INSTALL_DIR)
       else
diff --git a/perl/Makefile.config.in b/perl/Makefile.config.in
index c87d4817e..d08ee65db 100644
--- a/perl/Makefile.config.in
+++ b/perl/Makefile.config.in
@@ -1,3 +1,4 @@
+HOST_OS = @host_os@
 CC = @CC@
 CFLAGS = @CFLAGS@
 CXX = @CXX@
diff --git a/perl/configure.ac b/perl/configure.ac
index e8e3610a8..4ee6923a4 100644
--- a/perl/configure.ac
+++ b/perl/configure.ac
@@ -10,6 +10,8 @@ AC_PROG_CC
 AC_PROG_CXX
 AX_CXX_COMPILE_STDCXX_11
 
+AC_CANONICAL_HOST
+
 # Use 64-bit file system calls so that we can support files > 2 GiB.
 AC_SYS_LARGEFILE
 
diff --git a/perl/local.mk b/perl/local.mk
index b13d4c0d6..0eae651d8 100644
--- a/perl/local.mk
+++ b/perl/local.mk
@@ -28,7 +28,7 @@ Store_CXXFLAGS = \
 
 Store_LDFLAGS := $(SODIUM_LIBS) $(NIX_LIBS)
 
-ifeq (CYGWIN,$(findstring CYGWIN,$(OS)))
+ifdef HOST_CYGWIN
   archlib = $(shell perl -E 'use Config; print $$Config{archlib};')
   libperl = $(shell perl -E 'use Config; print $$Config{libperl};')
   Store_LDFLAGS += $(shell find ${archlib} -name ${libperl})
diff --git a/src/libexpr/local.mk b/src/libexpr/local.mk
index 00d6d75c1..e190022ff 100644
--- a/src/libexpr/local.mk
+++ b/src/libexpr/local.mk
@@ -9,7 +9,7 @@ libexpr_SOURCES := $(wildcard $(d)/*.cc) $(wildcard $(d)/primops/*.cc) $(d)/lexe
 libexpr_LIBS = libutil libstore
 
 libexpr_LDFLAGS =
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
  libexpr_LDFLAGS += -ldl
 endif
 
diff --git a/src/libstore/local.mk b/src/libstore/local.mk
index bc665f2cb..e9a9e804b 100644
--- a/src/libstore/local.mk
+++ b/src/libstore/local.mk
@@ -9,7 +9,7 @@ libstore_SOURCES := $(wildcard $(d)/*.cc $(d)/builtins/*.cc)
 libstore_LIBS = libutil
 
 libstore_LDFLAGS = $(SQLITE3_LIBS) -lbz2 $(LIBCURL_LIBS) $(SODIUM_LIBS) -pthread
-ifeq ($(OS), Linux)
+ifdef HOST_LINUX
  libstore_LDFLAGS += -ldl
 endif
 
@@ -21,7 +21,7 @@ ifeq ($(ENABLE_S3), 1)
 	libstore_LDFLAGS += -laws-cpp-sdk-transfer -laws-cpp-sdk-s3 -laws-cpp-sdk-core
 endif
 
-ifeq ($(OS), SunOS)
+ifdef HOST_SOLARIS
 	libstore_LDFLAGS += -lsocket
 endif
 
diff --git a/src/resolve-system-dependencies/local.mk b/src/resolve-system-dependencies/local.mk
index f9db16268..dbc041b23 100644
--- a/src/resolve-system-dependencies/local.mk
+++ b/src/resolve-system-dependencies/local.mk
@@ -1,4 +1,4 @@
-ifeq ($(OS), Darwin)
+ifdef HOST_DARWIN
   programs += resolve-system-dependencies
 endif