diff --git a/type/__matrix_synapse/files/homeserver.yaml.sh b/type/__matrix_synapse/files/homeserver.yaml.sh
index be924d3..d8e6653 100755
--- a/type/__matrix_synapse/files/homeserver.yaml.sh
+++ b/type/__matrix_synapse/files/homeserver.yaml.sh
@@ -1846,6 +1846,17 @@ cat << EOF
       # value will be used instead.
       #
       #mxid_mapping: dotreplace
+EOF
+
+if [ -n "$SAML2_MAPPING_PROVIDER_EXTRA_CONFIG" ]; then
+	echo "$SAML2_MAPPING_PROVIDER_EXTRA_CONFIG" | while IFS= read -r entry; do
+		cat << EOF
+      $entry
+EOF
+	done
+fi
+
+cat << EOF
 
   # In previous versions of synapse, the mapping from SAML attribute to
   # MXID was always calculated dynamically rather than stored in a
diff --git a/type/__matrix_synapse/man.rst b/type/__matrix_synapse/man.rst
index ace5ce0..7da9282 100644
--- a/type/__matrix_synapse/man.rst
+++ b/type/__matrix_synapse/man.rst
@@ -201,6 +201,10 @@ saml2-sp-cert
 saml2-mapping-provider-module
   Name of custom Python module used to map SAML2 attributes to synapse internals.
 
+saml2-mapping-provider-extra-settings
+  Extra YAML-formatted key/pair values provided as configuration to the SAML2
+  mapping provider module (e.g. 'key: value'). Can be specified multiple times.
+
 extra-setting
   Arbitrary string to be added to the configuration file. Can be specified multiple times.
 
diff --git a/type/__matrix_synapse/manifest b/type/__matrix_synapse/manifest
index 3d62a13..5a9871d 100755
--- a/type/__matrix_synapse/manifest
+++ b/type/__matrix_synapse/manifest
@@ -215,6 +215,11 @@ if [ -f "$__object/parameter/saml2-mapping-provider-module" ]; then
 	export SAML2_MAPPING_PROVIDER_MODULE
 fi
 
+if [ -f "$__object/parameter/saml2-mapping-provider-extra-config" ]; then
+	SAML2_MAPPING_PROVIDER_EXTRA_CONFIG=$(cat "$__object/parameter/saml2-mapping-provider-extra-config")
+	export SAML2_MAPPING_PROVIDER_EXTRA_CONFIG
+fi
+
 if [ -n "$SAML2_SP_KEY" ] && [ -z "$SAML2_SP_CERT" ]; then
 	echo "--saml2-sp-cert must be set if --saml2-sp-key is provided." >&2
 	exit 1
diff --git a/type/__matrix_synapse/parameter/optional_multiple b/type/__matrix_synapse/parameter/optional_multiple
index 8871dd6..dfd69cb 100644
--- a/type/__matrix_synapse/parameter/optional_multiple
+++ b/type/__matrix_synapse/parameter/optional_multiple
@@ -5,3 +5,4 @@ app-service-config-file
 extra-setting
 bind-address
 outbound-federation-worker
+saml2-mapping-provider-extra-config