diff --git a/+srv/expServer.m b/+srv/expServer.m
index 7fb3ca2f..7af7d14c 100644
--- a/+srv/expServer.m
+++ b/+srv/expServer.m
@@ -274,7 +274,8 @@ function handleMessage(id, data, host)
     rig.stimWindow.flip(); % clear the screen after
     
     % save a copy of the hardware in JSON
-    fid = fopen(dat.expFilePath(expRef, 'hw-info', 'master', 'json'), 'w');
+    hwInfo = dat.expFilePath(expRef, 'hw-info', 'master', 'json');
+    fid = fopen(hwInfo, 'w');
     fprintf(fid, '%s', obj2json(rig));
     fclose(fid);
     if ~strcmp(dat.parseExpRef(expRef), 'default')