diff --git a/guix/scripts/substitute-binary.scm b/guix/scripts/substitute-binary.scm
index fb2eb4dbe8180b88b571922fe9a05ecf0d19ce7a..e6244245d3abad133b83b5ef4585186f1ab6e909 100755
--- a/guix/scripts/substitute-binary.scm
+++ b/guix/scripts/substitute-binary.scm
@@ -107,7 +107,7 @@ (define (fields->alist port)
 
 (define %fetch-timeout
   ;; Number of seconds after which networking is considered "slow".
-  3)
+  5)
 
 (define %random-state
   (seed->random-state (+ (ash (cdr (gettimeofday)) 32) (getpid))))