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--- a/src/mk/Darwin
+++ b/src/mk/Darwin
@@ -4,7 +4,8 @@
 ALL_CXXFLAGS = $(CXXFLAGS) $(COMMONCXXFLAGS) $(LOCALCXXFLAGS) \
            -DPUTENV_ARG_NOT_CONST \
 	   -DHAVE_VASPRINTF=1 \
-	   -DHAVE_MKDTEMP=1
+	   -DHAVE_MKDTEMP=1 \
+	   -DSTATFS_INCLUDE="<sys/mount.h>"
 
 RANLIB = ranlib
 LIBSYS =