diff --git a/bindings/utils.scm b/bindings/utils.scm
index a6fa9e0..6c9e2c0 100644
--- a/bindings/utils.scm
+++ b/bindings/utils.scm
@@ -1,13 +1,13 @@
 ; Convert a char* to a Scheme string
 ; Extracted from this paper:
 ; http://scheme2011.ucombinator.org/papers/Keep2011.pdf
-(define (char*->string fptr)
+(define (char*->string fptr maxsize)
   (let f ([i 0])
     (let ([c (ftype-ref char () fptr i)])
-      (if (char=? c #\nul) 
+      (if (or (char=? c #\nul) (and (> maxsize 0) (>= i maxsize)))
           (make-string i)
           (let ([str (f (fx+ i 1))])
-            (string-set! str i c)str)))))
+            (string-set! str i c) str)))))
 
 (define (alloc size fx)
   (let ([v (foreign-alloc size)])
diff --git a/examples/udp_server.scm b/examples/udp_server.scm
index 2a18cb2..0b73843 100644
--- a/examples/udp_server.scm
+++ b/examples/udp_server.scm
@@ -84,5 +84,6 @@
           "host: ~a, port: ~a, size: ~a, buf: ~a~%"
           host port size 
           (char*->string
-            (make-ftype-pointer char buf)))
+            (make-ftype-pointer char buf)
+            size))
 ))))