diff --git a/reg-tests/sample_fetches/ubase64.vtc b/reg-tests/sample_fetches/ubase64.vtc
index d6973e3..0122bad 100644
--- a/reg-tests/sample_fetches/ubase64.vtc
+++ b/reg-tests/sample_fetches/ubase64.vtc
@@ -5,6 +5,12 @@
 feature ignore_unknown_macro
 
 haproxy h1 -conf {
+    global
+        # WT: limit false-positives causing "HTTP header incomplete" due to
+        # idle server connections being randomly used and randomly expiring
+        # under us.
+        tune.idle-pool.shared off
+
     defaults
         mode http
         timeout connect 1s