Index: uspace/lib/c/generic/str.c
===================================================================
--- uspace/lib/c/generic/str.c	(revision e99564dc2111119a734299639f28432400d665d2)
+++ uspace/lib/c/generic/str.c	(revision a8bc7f8ffbe7619c0a815a40e4d05bd262b5c6a6)
@@ -540,4 +540,7 @@
 
 	dstr_size = str_size(dest);
+	if (dstr_size >= size) {
+		return;
+	}
 	str_cpy(dest + dstr_size, size - dstr_size, src);
 }