diff --git a/lib/SyTest/Homeserver/Synapse.pm b/lib/SyTest/Homeserver/Synapse.pm
index 1d2d9d18d..023cafee1 100644
--- a/lib/SyTest/Homeserver/Synapse.pm
+++ b/lib/SyTest/Homeserver/Synapse.pm
@@ -33,6 +33,7 @@ sub _init
 
    $self->{paths} = {};
    $self->{dendron} = '';
+   $self->{redis_host} = '';
 
    $self->SUPER::_init( $args );
 
@@ -282,6 +283,11 @@ sub start
         limit_usage_by_mau => "true",
         max_mau_value => 50000000,
 
+        redis => {
+           enabled => $self->{redis_host} ne '',
+           host    => $self->{redis_host},
+        },
+
         map {
            defined $self->{$_} ? ( $_ => $self->{$_} ) : ()
         } qw(
@@ -653,6 +659,7 @@ sub _init
    $self->SUPER::_init( @_ );
 
    $self->{dendron} = delete $args->{dendron_binary};
+   $self->{redis_host} = delete $args->{redis_host};
 
    if( my $level = delete $args->{torture_replication} ) {
       # torture the replication protocol a bit, to replicate bugs.
diff --git a/lib/SyTest/HomeserverFactory/Synapse.pm b/lib/SyTest/HomeserverFactory/Synapse.pm
index 5849e584f..49a75c7af 100644
--- a/lib/SyTest/HomeserverFactory/Synapse.pm
+++ b/lib/SyTest/HomeserverFactory/Synapse.pm
@@ -101,6 +101,7 @@ sub _init
    $self->{impl} = "SyTest::Homeserver::Synapse::ViaDendron";
    $self->{args}{dendron_binary} = "";
    $self->{args}{torture_replication} = 0;
+   $self->{args}{redis_host} = "";
 }
 
 sub get_options
@@ -108,8 +109,9 @@ sub get_options
    my $self = shift;
 
    return (
-      'dendron-binary=s' => \$self->{args}{dendron_binary},
+      'dendron-binary=s'       => \$self->{args}{dendron_binary},
       'torture-replication:50' => \$self->{args}{torture_replication},
+      'redis-host=s'           => \$self->{args}{redis_host},
       $self->SUPER::get_options(),
    );
 }
@@ -125,6 +127,8 @@ sub print_usage
        --dendron-binary PATH    - path to the 'dendron' binary
 
        --torture-replication[=LEVEL] - enable torturing of the replication protocol
+
+       --redis-host HOST 	- if set then use redis for replication
 EOF
 }
 
diff --git a/scripts/synapse_sytest.sh b/scripts/synapse_sytest.sh
index d13c8b2d1..599e4392a 100755
--- a/scripts/synapse_sytest.sh
+++ b/scripts/synapse_sytest.sh
@@ -121,7 +121,7 @@ if [ -n "$OFFLINE" ]; then
 else
     # We've already created the virtualenv, but lets double check we have all
     # deps.
-    /venv/bin/pip install -q --upgrade --no-cache-dir /src
+    /venv/bin/pip install -q --upgrade --no-cache-dir /src[redis]
     /venv/bin/pip install -q --upgrade --no-cache-dir \
         lxml psycopg2 coverage codecov tap.py coverage_enable_subprocess