diff --git a/c_stuff/Makefile b/c_stuff/Makefile
index 08e71f9..f525263 100644
--- a/c_stuff/Makefile
+++ b/c_stuff/Makefile
@@ -25,6 +25,11 @@ ifdef INSTALLSITELIB
 else
    PMO_INSTALLSITELIB=
 endif
+ifdef INSTALLSITEARCH
+    PMO_INSTALLSITEARCH=INSTALLSITEARCH=$(INSTALLSITEARCH)
+else
+   PMO_INSTALLSITEARCH=
+endif
 ifdef INSTALLBIN
     PMO_INSTALLBIN=INSTALLBIN=$(INSTALLBIN)
 else
@@ -42,8 +47,8 @@ else
 endif
 
 PERL_MAKE_OPTS = $(PMO_PREFIX) $(PMO_INSTALLPRIVLIB) $(PMO_INSTALLSCRIPT) \
-    $(PMO_INSTALLSITELIB) $(PMO_INSTALLBIN) $(PMO_INSTALLMAN1DIR) \
-    $(PMO_INSTALLMAN3DIR)
+    $(PMO_INSTALLSITELIB) $(PMO_INSTALLSITEARCH) $(PMO_INSTALLBIN) \
+    $(PMO_INSTALLMAN1DIR) $(PMO_INSTALLMAN3DIR)
 
 Makefile_c: Makefile.PL
 	perl Makefile.PL $(PERL_MAKE_OPTS) INSTALLDIRS=$(INSTALLDIRS)