diff --git a/jenkins-dendron-postgres.sh b/jenkins-dendron-postgres.sh
index 7e6f24aa7d6c082fe4b9999226ad8471a24bff88..50268e0982ac81f7eaa6f65335b7142cf4dd083f 100755
--- a/jenkins-dendron-postgres.sh
+++ b/jenkins-dendron-postgres.sh
@@ -70,6 +70,7 @@ cd sytest
 git checkout "${GIT_BRANCH}" || (echo >&2 "No ref ${GIT_BRANCH} found, falling back to develop" ; git checkout develop)
 
 : ${PORT_BASE:=8000}
+: ${PORT_COUNT=20}
 
 ./jenkins/prep_sytest_for_postgres.sh
 
@@ -81,6 +82,6 @@ echo >&2 "Running sytest with PostgreSQL";
                              --dendron $WORKSPACE/dendron/bin/dendron \
                              --pusher \
                              --synchrotron \
-                             --port-base $PORT_BASE
+                             --port-range ${PORT_BASE}:$((PORT_BASE+PORT_COUNT-1))
 
 cd ..
diff --git a/jenkins-postgres.sh b/jenkins-postgres.sh
index ae6b111591038373e3aefb003a0b74f8d756083f..2f0768fcb7a85a6867b1a60c0b5990e3c4cad395 100755
--- a/jenkins-postgres.sh
+++ b/jenkins-postgres.sh
@@ -44,6 +44,7 @@ cd sytest
 git checkout "${GIT_BRANCH}" || (echo >&2 "No ref ${GIT_BRANCH} found, falling back to develop" ; git checkout develop)
 
 : ${PORT_BASE:=8000}
+: ${PORT_COUNT=20}
 
 ./jenkins/prep_sytest_for_postgres.sh
 
@@ -51,7 +52,7 @@ echo >&2 "Running sytest with PostgreSQL";
 ./jenkins/install_and_run.sh --coverage \
                              --python $TOX_BIN/python \
                              --synapse-directory $WORKSPACE \
-                             --port-base $PORT_BASE
+                             --port-range ${PORT_BASE}:$((PORT_BASE+PORT_COUNT-1)) \
 
 cd ..
 cp sytest/.coverage.* .
diff --git a/jenkins-sqlite.sh b/jenkins-sqlite.sh
index 9398d9db1545678342a08922538d1f84bda052b0..da603c5af8ef6c038d08912ebb51c9748ae671c6 100755
--- a/jenkins-sqlite.sh
+++ b/jenkins-sqlite.sh
@@ -41,11 +41,12 @@ cd sytest
 
 git checkout "${GIT_BRANCH}" || (echo >&2 "No ref ${GIT_BRANCH} found, falling back to develop" ; git checkout develop)
 
-: ${PORT_BASE:=8500}
+: ${PORT_COUNT=20}
+: ${PORT_BASE:=8000}
 ./jenkins/install_and_run.sh --coverage \
                              --python $TOX_BIN/python \
                              --synapse-directory $WORKSPACE \
-                             --port-base $PORT_BASE
+                             --port-range ${PORT_BASE}:$((PORT_BASE+PORT_COUNT-1)) \
 
 cd ..
 cp sytest/.coverage.* .