diff --git a/src/github.com/matrix-org/dendrite/cmd/mediaapi-integration-tests/main.go b/src/github.com/matrix-org/dendrite/cmd/mediaapi-integration-tests/main.go
index 13c83c5de..9902f4ef8 100644
--- a/src/github.com/matrix-org/dendrite/cmd/mediaapi-integration-tests/main.go
+++ b/src/github.com/matrix-org/dendrite/cmd/mediaapi-integration-tests/main.go
@@ -37,7 +37,7 @@ var (
 	postgresDatabase = test.Defaulting(os.Getenv("POSTGRES_DATABASE"), "postgres")
 	// The name of the test database to create.
 	testDatabaseName = test.Defaulting(os.Getenv("DATABASE_NAME"), "mediaapi_test")
-	// Postgres docker container name (for running psql)
+	// Postgres docker container name (for running psql). If not set, psql must be in PATH.
 	postgresContainerName = os.Getenv("POSTGRES_CONTAINER")
 	// Test image to be uploaded/downloaded
 	testJPEG = test.Defaulting(os.Getenv("TEST_JPEG_PATH"), "src/github.com/matrix-org/dendrite/cmd/mediaapi-integration-tests/totem.jpg")
diff --git a/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go b/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
index 4f1786fab..b73405583 100644
--- a/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
+++ b/src/github.com/matrix-org/dendrite/cmd/syncserver-integration-tests/main.go
@@ -43,7 +43,7 @@ var (
 	timeoutString = test.Defaulting(os.Getenv("TIMEOUT"), "10s")
 	// The name of maintenance database to connect to in order to create the test database.
 	postgresDatabase = test.Defaulting(os.Getenv("POSTGRES_DATABASE"), "postgres")
-	// Postgres docker container name (for running psql)
+	// Postgres docker container name (for running psql). If not set, psql must be in PATH.
 	postgresContainerName = os.Getenv("POSTGRES_CONTAINER")
 	// The name of the test database to create.
 	testDatabaseName = test.Defaulting(os.Getenv("DATABASE_NAME"), "syncserver_test")
diff --git a/src/github.com/matrix-org/dendrite/common/test/server.go b/src/github.com/matrix-org/dendrite/common/test/server.go
index 6e670d372..dca0aa94c 100644
--- a/src/github.com/matrix-org/dendrite/common/test/server.go
+++ b/src/github.com/matrix-org/dendrite/common/test/server.go
@@ -67,6 +67,8 @@ func CreateBackgroundCommand(command string, args []string) (*exec.Cmd, chan err
 // StartServer creates the database and config file needed for the server to run and
 // then starts the server. The Cmd being executed is returned. A channel is also returned,
 // which will have any termination errors sent down it, followed immediately by the channel being closed.
+// If postgresContainerName is not an empty string, psql will be run from inside that container. If it is
+// an empty string, psql will be assumed to be in PATH.
 func StartServer(serverType string, serverArgs []string, suffix, configFilename, configFileContents, postgresDatabase, postgresContainerName string, databases []string) (*exec.Cmd, chan error) {
 	if len(databases) > 0 {
 		var dbCmd string