diff --git a/tests/timeout.nix b/tests/timeout.nix
index 540fba934..e18d717ef 100644
--- a/tests/timeout.nix
+++ b/tests/timeout.nix
@@ -5,6 +5,7 @@ with import ./config.nix;
   infiniteLoop = mkDerivation {
     name = "timeout";
     buildCommand = ''
+      touch $out
       echo "‘timeout’ builder entering an infinite loop"
       while true ; do echo -n .; done
     '';
@@ -13,6 +14,7 @@ with import ./config.nix;
   silent = mkDerivation {
     name = "silent";
     buildCommand = ''
+      touch $out
       sleep 60
     '';
   };
@@ -20,6 +22,7 @@ with import ./config.nix;
   closeLog = mkDerivation {
     name = "silent";
     buildCommand = ''
+      touch $out
       exec > /dev/null 2>&1
       sleep 1000000000
     '';