diff --git a/charts/matrix-synapse/templates/_helpers.tpl b/charts/matrix-synapse/templates/_helpers.tpl
index 06425a9..aa70880 100644
--- a/charts/matrix-synapse/templates/_helpers.tpl
+++ b/charts/matrix-synapse/templates/_helpers.tpl
@@ -186,6 +186,17 @@ Set postgresql database
 {{- end -}}
 {{- end -}}
 
+{{/*
+Set postgresql sslmode
+*/}}
+{{- define "matrix-synapse.postgresql.sslmode" -}}
+{{- if .Values.postgresql.enabled -}}
+{{- default "prefer" .Values.postgresql.sslmode }}
+{{- else -}}
+{{- default "prefer" .Values.externalPostgresql.sslmode }}
+{{- end -}}
+{{- end -}}
+
 {{/*
 Set redis host
 */}}
diff --git a/charts/matrix-synapse/templates/secrets.yaml b/charts/matrix-synapse/templates/secrets.yaml
index e7b30d4..4b69c56 100644
--- a/charts/matrix-synapse/templates/secrets.yaml
+++ b/charts/matrix-synapse/templates/secrets.yaml
@@ -35,6 +35,7 @@ stringData:
 {{- $postgresUser := include "matrix-synapse.postgresql.username" . }}
 {{- $postgresPort := include "matrix-synapse.postgresql.port" . }}
 {{- $postgresPass := include "matrix-synapse.postgresql.password" . }}
+{{- $postgresSSLMode := include "matrix-synapse.postgresql.sslmode" . }}
 
     ## Database configuration ##
 
@@ -50,6 +51,7 @@ stringData:
         database: {{ $postgresDB | quote }}
         host: {{ $postgresHost | quote }}
         port: {{ $postgresPort }}
+        sslmode: {{ $postgresSSLMode | quote }}
         cp_min: 5
         cp_max: 10
 
diff --git a/charts/matrix-synapse/values.yaml b/charts/matrix-synapse/values.yaml
index cb38ddb..4c32b2c 100644
--- a/charts/matrix-synapse/values.yaml
+++ b/charts/matrix-synapse/values.yaml
@@ -555,7 +555,7 @@ externalPostgresql:
   username: synapse
   # password: synapse
   database: synapse
-  # sslMode: require
+  # sslmode: prefer
 
 ## This configuration is for the internal Redis that's deployed for use with
 ## workers/sharding, for an external Redis server you want to set enabled to