diff --git a/include/Protocol/Lifecycle.h b/include/Protocol/Lifecycle.h
index 9c804ec3..207a6bfc 100644
--- a/include/Protocol/Lifecycle.h
+++ b/include/Protocol/Lifecycle.h
@@ -64,7 +64,14 @@ struct InitializeParams {
     /// This property is only available if the client supports workspace folders.
     /// It can be `null` if the client supports workspace folders but none are
     /// configured.
-    array<WorkspaceFolder> workspaceFolders;
+    optional<array<WorkspaceFolder>> workspaceFolders;
+
+    /// The rootUri of the workspace. Is null if no
+    /// folder is open. If both `rootPath` and `rootUri` are set
+    /// `rootUri` wins.
+    ///
+    /// Deprecated in favour of `workspaceFolders`
+    optional<URI> rootUri;
 };
 
 struct ServerCapabilities {
diff --git a/src/Server/Lifecycle.cpp b/src/Server/Lifecycle.cpp
index 8635f8f5..725ac237 100644
--- a/src/Server/Lifecycle.cpp
+++ b/src/Server/Lifecycle.cpp
@@ -7,13 +7,18 @@ async::Task<json::Value> Server::on_initialize(proto::InitializeParams params) {
               params.clientInfo.name,
               params.clientInfo.verion);
 
-    if(params.workspaceFolders.empty()) {
-        log::fatal("The client should provide one workspace folder at least!");
-    }
-
     /// FIXME: adjust position encoding.
     kind = PositionEncodingKind::UTF16;
-    workspace = mapping.to_path(params.workspaceFolders[0].uri);
+    workspace = mapping.to_path(([&] -> std::string {
+        if(params.workspaceFolders && !params.workspaceFolders->empty()) {
+            return params.workspaceFolders->front().uri;
+        }
+        if(params.rootUri) {
+            return *params.rootUri;
+        }
+
+        log::fatal("The client should provide one workspace folder or rootUri at least!");
+    })());
 
     /// Initialize configuration.
     config::init(workspace);