diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b5dc5fe..1ba5126 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -22,9 +22,9 @@ jobs:
         pip install -r requirements.txt
         python setup.py install
     - name: Setup Singularity
-      uses: eWaterCycle/setup-singularity@v3
+      uses: eWaterCycle/setup-singularity@v4
       with:
-        singularity-version: 3.5.3
+        singularity-version: 3.6.4
     - name: Pull Docker image
       run: docker pull ewatercycle/walrus-grpc4bmi:v0.3.1
     - name: Cache Singularity image
diff --git a/grpc4bmi/bmi_client_singularity.py b/grpc4bmi/bmi_client_singularity.py
index 13a7704..f5b7cda 100644
--- a/grpc4bmi/bmi_client_singularity.py
+++ b/grpc4bmi/bmi_client_singularity.py
@@ -1,8 +1,8 @@
 import errno
 import os
+import time
 from os.path import abspath
 import subprocess
-import sys
 import logging
 
 from semver import VersionInfo
@@ -10,7 +10,7 @@
 from grpc4bmi.bmi_grpc_client import BmiClient
 from grpc4bmi.utils import stage_config_file
 
-REQUIRED_SINGULARITY_VERSION = '>=3.1.0'
+REQUIRED_SINGULARITY_VERSION = '>=3.6.0'
 
 
 def check_singularity_version():
@@ -41,6 +41,7 @@ class BmiClientSingularity(BmiClient):
         input_dir (str): Directory for input files of model
         output_dir (str): Directory for input files of model
         timeout (int): Seconds to wait for gRPC client to connect to server
+        delay (int): Seconds to wait for Singularity container to startup, before connecting to it
         extra_volumes (Dict[str,str]): Extra volumes to attach to Singularity container.
 
             The key is the hosts path and the value the mounted volume inside the container.
@@ -56,13 +57,15 @@ class BmiClientSingularity(BmiClient):
     INPUT_MOUNT_POINT = "/data/input"
     OUTPUT_MOUNT_POINT = "/data/output"
 
-    def __init__(self, image, input_dir=None, output_dir=None, timeout=None, extra_volumes=None):
+    def __init__(self, image, input_dir=None, output_dir=None, timeout=None,
+                 delay=0, extra_volumes=None):
         check_singularity_version()
         host = 'localhost'
         port = BmiClient.get_unique_port(host)
         args = [
             "singularity",
             "run",
+            "--env", f"BMI_PORT={port}"
         ]
         mount_points = {} if extra_volumes is None else extra_volumes
         if input_dir is not None:
@@ -80,10 +83,9 @@ def __init__(self, image, input_dir=None, output_dir=None, timeout=None, extra_v
                     raise e
             args += ["--bind", output_dir + ':' + BmiClientSingularity.OUTPUT_MOUNT_POINT]
         args.append(image)
-        env = os.environ.copy()
-        env['BMI_PORT'] = str(port)
         logging.info(f'Running {image} singularity container on port {port}')
-        self.container = subprocess.Popen(args, env=env, preexec_fn=os.setsid)
+        self.container = subprocess.Popen(args, preexec_fn=os.setsid)
+        time.sleep(delay)
         super(BmiClientSingularity, self).__init__(BmiClient.create_grpc_channel(port=port, host=host), timeout=timeout)
 
     def __del__(self):
diff --git a/setup.py b/setup.py
index 21f11ea..23e003e 100644
--- a/setup.py
+++ b/setup.py
@@ -11,7 +11,7 @@ def read(fname):
 
 
 setup(name="grpc4bmi",
-      version="0.3.1",
+      version="0.3.2",
       author="Gijs van den Oord",
       author_email="g.vandenoord@esciencecenter.nl",
       description="Run your BMI implementation in a separate process and expose it as BMI-python with GRPC",