diff --git a/src/userfunc.c b/src/userfunc.c
index a739a75..2bdc2b1 100644
--- a/src/userfunc.c
+++ b/src/userfunc.c
@@ -288,7 +288,7 @@
 
 	sprintf((char*)name, "<lambda>%d", ++lambda_no);
 
-	fp = alloc_clear(sizeof(ufunc_T) + STRLEN(name));
+	fp = alloc_clear(offsetof(ufunc_T, uf_name) + STRLEN(name) + 1);
 	if (fp == NULL)
 	    goto errret;
 	pt = ALLOC_CLEAR_ONE(partial_T);
@@ -2631,7 +2631,7 @@
 	    }
 	}
 
-	fp = alloc_clear(sizeof(ufunc_T) + STRLEN(name));
+	fp = alloc_clear(offsetof(ufunc_T, uf_name) + STRLEN(name) + 1);
 	if (fp == NULL)
 	    goto erret;