--- a/perform/pio_engine.c
+++ b/perform/pio_engine.c
@@ -454,7 +454,7 @@
         subdir = (user ? user : login);
 
         if (subdir) {
-            for (i = 0; i < size && prefix[i]; i++)
+            for (i = 0; i < size-1 && prefix[i]; i++)
                 fullname[i] = prefix[i];
 
             fullname[i++] = '/';
--- a/perform/sio_engine.c
+++ b/perform/sio_engine.c
@@ -353,7 +353,7 @@
     subdir = (user ? user : login);
 
     if (subdir) {
-        for (i = 0; i < size && prefix[i]; i++)
+        for (i = 0; i < size-1 && prefix[i]; i++)
         fullname[i] = prefix[i];
 
         fullname[i++] = '/';