diff --git a/Makefile.am b/Makefile.am
index 96c4ae2..edd6077 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -26,6 +26,9 @@
   MAYBE_W32 =	w32
   W32INC =	-I $(top_srcdir)/w32/include
   W32LIB =	-Lw32 -lw32
+  ossrc =
+else
+  ossrc =	posixos.c
 endif
 
 SUBDIRS =	glob config po doc $(MAYBE_W32)
@@ -41,7 +44,7 @@
 
 make_SOURCES =	ar.c arscan.c commands.c default.c dir.c expand.c file.c \
 		function.c getopt.c getopt1.c guile.c implicit.c job.c load.c \
-		loadapi.c main.c misc.c output.c posixos.c read.c remake.c \
+		loadapi.c main.c misc.c $(ossrc) output.c read.c remake.c \
 		rule.c signame.c strcache.c variable.c version.c vpath.c \
 		hash.c $(remote)
 
diff --git a/w32/Makefile.am b/w32/Makefile.am
index af97768..b0b4734 100644
--- a/w32/Makefile.am
+++ b/w32/Makefile.am
@@ -20,6 +20,6 @@
 noinst_LIBRARIES = libw32.a
 
 libw32_a_SOURCES =  subproc/misc.c subproc/sub_proc.c subproc/w32err.c \
-		    compat/posixfcn.c pathstuff.c
+		    compat/posixfcn.c pathstuff.c w32os.c
 
 libw32_a_CPPFLAGS = -I$(srcdir)/include -I$(srcdir)/subproc -I$(top_srcdir)