diff --git a/src/libsystemd/sd-bus/bus-internal.h b/src/libsystemd/sd-bus/bus-internal.h
index 2087ef8eeb..4c07d55b61 100644
--- a/src/libsystemd/sd-bus/bus-internal.h
+++ b/src/libsystemd/sd-bus/bus-internal.h
@@ -384,7 +384,7 @@ void bus_close_io_fds(sd_bus *b);
 
 #define OBJECT_PATH_FOREACH_PREFIX(prefix, path)                        \
         for (char *_slash = ({ strcpy((prefix), (path)); streq((prefix), "/") ? NULL : strrchr((prefix), '/'); }) ; \
-             _slash && !(_slash[(_slash) == (prefix)] = 0);             \
+             _slash && ((_slash[(_slash) == (prefix)] = 0), true);       \
              _slash = streq((prefix), "/") ? NULL : strrchr((prefix), '/'))
 
 /* If we are invoking callbacks of a bus object, ensure unreffing the