diff --git a/pb.h b/pb.h
index 85f4421..f894a9a 100644
--- a/pb.h
+++ b/pb.h
@@ -194,7 +194,7 @@ typedef enum {
 #define pb_arraysize(st, m) (pb_membersize(st, m) / pb_membersize(st, m[0]))
 #define pb_delta(st, m1, m2) ((int)offsetof(st, m1) - (int)offsetof(st, m2))
 #define pb_delta_end(st, m1, m2) (offsetof(st, m1) - offsetof(st, m2) - pb_membersize(st, m2))
-#define PB_LAST_FIELD {0,(pb_type_t) 0,0,0}
+#define PB_LAST_FIELD {0,(pb_type_t) 0,0,0,0,0,0}
 
 /* These macros are used for giving out error messages.
  * They are mostly a debugging aid; the main error information
diff --git a/tests/Makefile b/tests/Makefile
index 3810c95..e4c67c5 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -11,6 +11,9 @@ all: breakpoints $(TESTS) run_unittests
 clean:
 	rm -f $(TESTS) person.pb* alltypes.pb* *.o *.gcda *.gcno
 
+%.pb.o: %.pb.c %.pb.h
+	$(CC) $(CFLAGS) $(CFLAGS_CORE) -c -o $@ $<
+
 %.o: %.c
 %.o: %.c $(DEPS)
 	$(CC) $(CFLAGS) -c -o $@ $<