diff --git a/src/plugin.c b/src/plugin.c
index 2f89b01d..0a3d7051 100644
--- a/src/plugin.c
+++ b/src/plugin.c
@@ -126,7 +126,7 @@ wPluginDestroyFunction(WFunction *function)
 
     if (function->data) {
         if (function->freeData) {
-            function->freeData(&function->data);
+            function->freeData(function->arg, &function->data);
         } else {
             wfree(function->data);
         }
diff --git a/src/plugin.h b/src/plugin.h
index b6dae22b..8fa758ab 100644
--- a/src/plugin.h
+++ b/src/plugin.h
@@ -53,7 +53,7 @@ typedef void _DL_AnyProc(proplist_t);
 typedef void _DL_DrawStringProc(proplist_t, Drawable, GC, WMFont *, int, int, unsigned, unsigned, char *, int);
 #endif
 
-typedef void _DL_FreeDataProc(void *free_me);
+typedef void _DL_FreeDataProc(proplist_t pl, void *free_data);
 
 typedef int _DL_InitDataProc(proplist_t pl, void *init_data); /* prototype
                                                                  for function