diff --git a/src/api/dirmonitor/dummy.c b/src/api/dirmonitor/dummy.c
index 47aa0990..0690f61d 100644
--- a/src/api/dirmonitor/dummy.c
+++ b/src/api/dirmonitor/dummy.c
@@ -2,7 +2,7 @@
 
 struct dirmonitor_internal* init_dirmonitor() { return NULL; }
 void deinit_dirmonitor(struct dirmonitor_internal* monitor) { }
-int get_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, size_t len) { return -1; }
+int get_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int len) { return -1; }
 int translate_changes_dirmonitor(struct dirmonitor_internal* monitor, char* buffer, int size, int (*callback)(int, const char*, void*), void* data) { return -1; }
 int add_dirmonitor(struct dirmonitor_internal* monitor, const char* path) { return -1; }
 void remove_dirmonitor(struct dirmonitor_internal* monitor, int fd) { }