diff --git a/unit-tests/020_ext-verifier.txt b/unit-tests/020_ext-verifier.txt
new file mode 100644
index 0000000..a2e0b92
--- /dev/null
+++ b/unit-tests/020_ext-verifier.txt
@@ -0,0 +1,33 @@
+# vim: ft=sh et :
+#
+# Testing whether the external verifier (before-acquire-handler)
+# is obeyed.
+
+
+ticket:
+    state               ST_STABLE
+    last_ack_ballot     40
+    new_ballot          50
+    owner               local
+    retries             6
+    timeout             1
+    # may keep ticket all the time
+    expiry              3000
+    # but shall start renewal now
+    expires             time(0) + 1000
+
+
+
+outgoing0:
+    header.cmd          OP_PREPARING
+
+# now say that we may not have it anymore.
+
+ticket1:
+    ext_verifier        "/bin/false"
+
+outgoing2:
+
+finally:
+    ticket.state        ST_INIT
+    ticket.owner        NULL
diff --git a/unit-tests/booth.conf b/unit-tests/booth.conf
index 971138d..5a69acb 100644
--- a/unit-tests/booth.conf
+++ b/unit-tests/booth.conf
@@ -1,15 +1,18 @@
 # "local"
 site=127.0.0.1
 
 # these should not exist, although it shouldn't matter much
 # because no packets should be sent anyway
 arbitrator="127.0.0.243"
 site="127.0.0.244"
 
 # The ticket name, which corresponds to a set of resources which can be
 # fail-overed among different sites.
 ticket="ticket"
 	expire = 60
 	timeout = 1
 	acquire-after = 30	
 	weights = 1,2,3
+
+	# make it non-critical, put provide enough space to override if necessary.
+	before-acquire-handler = "//////////////////////////////////bin/true"