diff --git a/tests/acceptance/ld_preload.rb b/tests/acceptance/ld_preload.rb
index 6ebf3cc..8ce0a8f 100644
--- a/tests/acceptance/ld_preload.rb
+++ b/tests/acceptance/ld_preload.rb
@@ -39,4 +39,9 @@ module LdPreload
       l.split(':').map { |i| i =~ /^\d+$/ ? i.to_i : i }
     end
   end
+
+  def assert_func_call(loglines, args, msg)
+    re = Regexp.new('^' + args.join(':'))
+    assert(loglines.any? { |l| l.match(re) }, msg)
+  end
 end
diff --git a/tests/acceptance/ld_preloads/setsockopt_logger.c b/tests/acceptance/ld_preloads/setsockopt_logger.c
index 08f3142..9a7bf60 100644
--- a/tests/acceptance/ld_preloads/setsockopt_logger.c
+++ b/tests/acceptance/ld_preloads/setsockopt_logger.c
@@ -26,7 +26,7 @@ int setsockopt(int sockfd, int level, int optname, const void *optval, socklen_t
   fn = getenv("OUTPUT_setsockopt_logger");
   if ( fn != NULL && optval != NULL && optlen == 4) {
     fd = fopen(fn,"a");
-    fprintf(fd,"setsockopt:%d:%d:%i:%d\n", level, optname, *(int *)optval, retval);
+    fprintf(fd,"setsockopt:%d:%d:%d:%i:%d\n", sockfd, level, optname, *(int *)optval, retval);
     fclose(fd);
   }
 
diff --git a/tests/acceptance/proxy_tests.rb b/tests/acceptance/proxy_tests.rb
index 65fe38a..ab68f44 100644
--- a/tests/acceptance/proxy_tests.rb
+++ b/tests/acceptance/proxy_tests.rb
@@ -147,45 +147,58 @@ module ProxyTests
   def test_write_request_retried_when_upstream_dies_partway
     maker = make_fake_server
 
-    with_proxied_client(4096) do |client|
-      server, sc1 = maker.value
+    with_ld_preload('setsockopt_logger') do
+      with_proxied_client(4096) do |client|
+        server, sc1 = maker.value
 
-      # Send the read request to the proxy
-      client.write(0, (b * 4096))
+        # Send the read request to the proxy
+        client.write(0, (b * 4096))
 
-      # ensure we're given the read request
-      req1 = sc1.read_request
-      assert_equal ::FlexNBD::REQUEST_MAGIC, req1[:magic]
-      assert_equal ::FlexNBD::REQUEST_WRITE, req1[:type]
-      assert_equal 0, req1[:from]
-      assert_equal 4096, req1[:len]
-      data1 = sc1.read_data(4096)
-      assert_equal((b * 4096), data1, 'Data not proxied successfully')
+        # ensure we're given the read request
+        req1 = sc1.read_request
+        assert_equal ::FlexNBD::REQUEST_MAGIC, req1[:magic]
+        assert_equal ::FlexNBD::REQUEST_WRITE, req1[:type]
+        assert_equal 0, req1[:from]
+        assert_equal 4096, req1[:len]
+        data1 = sc1.read_data(4096)
+        assert_equal((b * 4096), data1, 'Data not proxied successfully')
 
-      # Kill the server again, now we're sure the read request has been sent once
-      sc1.close
+        # Read the setsockopt logs, so we can check that TCP_NODELAY is re-set
+        # later
+        read_ld_preload_log('setsockopt_logger')
 
-      # We expect the proxy to reconnect without our client doing anything.
-      sc2 = server.accept
-      sc2.write_hello
+        # Kill the server again, now we're sure the read request has been sent once
+        sc1.close
 
-      # And once reconnected, it should resend an identical request.
-      req2 = sc2.read_request
-      assert_equal req1, req2
-      data2 = sc2.read_data(4096)
-      assert_equal data1, data2
+        # We expect the proxy to reconnect without our client doing anything.
+        sc2 = server.accept
+        sc2.write_hello
 
-      # The reply should be proxied back to the client.
-      sc2.write_reply(req2[:handle])
+        # And once reconnected, it should resend an identical request.
+        req2 = sc2.read_request
+        assert_equal req1, req2
+        data2 = sc2.read_data(4096)
+        assert_equal data1, data2
 
-      # Check it to make sure it's correct
-      rsp = Timeout.timeout(15) { client.read_response }
-      assert_equal ::FlexNBD::REPLY_MAGIC, rsp[:magic]
-      assert_equal 0, rsp[:error]
-      assert_equal req1[:handle], rsp[:handle]
+        # The reply should be proxied back to the client.
+        sc2.write_reply(req2[:handle])
 
-      sc2.close
-      server.close
+        # Check it to make sure it's correct
+        rsp = Timeout.timeout(15) { client.read_response }
+        assert_equal ::FlexNBD::REPLY_MAGIC, rsp[:magic]
+        assert_equal 0, rsp[:error]
+        assert_equal req1[:handle], rsp[:handle]
+
+        sc2.close
+        server.close
+
+        # Check TCP_NODELAY was set on the upstream socket
+        log = read_ld_preload_log('setsockopt_logger')
+        assert_func_call(log,
+                         ['setsockopt', 3,
+                          Socket::SOL_TCP, Socket::TCP_NODELAY, 1, 0],
+                         'TCP_NODELAY not set on upstream fd 3')
+      end
     end
   end
 
diff --git a/tests/acceptance/test_proxy_mode.rb b/tests/acceptance/test_proxy_mode.rb
index 87d10e2..d2e98c1 100644
--- a/tests/acceptance/test_proxy_mode.rb
+++ b/tests/acceptance/test_proxy_mode.rb
@@ -1,8 +1,11 @@
 require 'test/unit'
 require 'environment'
+require 'ld_preload'
 require 'proxy_tests'
 
 class TestProxyMode < Test::Unit::TestCase
+
+  include LdPreload
   include ProxyTests
 
   def setup
diff --git a/tests/acceptance/test_serve_mode.rb b/tests/acceptance/test_serve_mode.rb
index cc392d6..6c3e3f6 100644
--- a/tests/acceptance/test_serve_mode.rb
+++ b/tests/acceptance/test_serve_mode.rb
@@ -188,11 +188,23 @@ class TestServeMode < Test::Unit::TestCase
   def test_server_sets_tcpkeepalive
     with_ld_preload('setsockopt_logger') do
       connect_to_server(&:close)
-      op = parse_ld_preload_logs('setsockopt_logger')
-      assert(op.any? { |e| e == ['setsockopt', Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, 1, 0] }, 'TCP Keepalive not successfully set')
-      assert(op.any? { |e| e == ['setsockopt', Socket::SOL_TCP, Socket::TCP_KEEPIDLE, 30, 0] },  'TCP Keepalive idle timeout not set to 30s')
-      assert(op.any? { |e| e == ['setsockopt', Socket::SOL_TCP, Socket::TCP_KEEPINTVL, 10, 0] }, 'TCP keepalive retry time not set to 10s')
-      assert(op.any? { |e| e == ['setsockopt', Socket::SOL_TCP, Socket::TCP_KEEPCNT, 3, 0] }, 'TCP keepalive count not set to 3')
+      op = read_ld_preload_log('setsockopt_logger')
+      assert_func_call(op,
+                       ['setsockopt', '\d+',
+                        Socket::SOL_SOCKET, Socket::SO_KEEPALIVE, 1, 0],
+                       'TCP Keepalive not successfully set')
+      assert_func_call(op,
+                       ['setsockopt', '\d+',
+                        Socket::SOL_TCP, Socket::TCP_KEEPIDLE, 30, 0],
+                       'TCP Keepalive idle timeout not set to 30s')
+      assert_func_call(op,
+                       ['setsockopt', '\d+',
+                        Socket::SOL_TCP, Socket::TCP_KEEPINTVL, 10, 0],
+                       'TCP keepalive retry time not set to 10s')
+      assert_func_call(op,
+                       ['setsockopt', '\d+',
+                        Socket::SOL_TCP, Socket::TCP_KEEPCNT, 3, 0],
+                       'TCP keepalive count not set to 3')
     end
   end
 end