diff --git a/lean4-mode/lean4-flycheck.el b/lean4-mode/lean4-flycheck.el
index 62a7b23456..888cb89057 100644
--- a/lean4-mode/lean4-flycheck.el
+++ b/lean4-mode/lean4-flycheck.el
@@ -23,9 +23,7 @@
   (let ((command
          (-concat `(,(lean4-get-executable lean4-executable-name))
                   lean4-extra-arguments
-                  '("--json")
-                  '("--")
-                  '(source-inplace))))
+                  '("--json" "--stdin"))))
     command))
 
 (cl-defun lean4-flycheck-parse-task (checker buffer cur-file-name
@@ -77,7 +75,7 @@
                            ("information" 'info)
                            (_ 'info))
                          (lean4-info-fontify-string text)
-                         :filename file_name
+                         :filename (if (equal file_name "<stdin>") nil file_name)
                          :checker checker :buffer buffer))
 
 (defun lean4-flycheck-parse-errors (output checker buffer)
@@ -105,6 +103,7 @@
   (flycheck-define-command-checker 'lean4-checker
     "A Lean syntax checker."
     :command (lean4-flycheck-command)
+    :standard-input t
     :error-parser #'lean4-flycheck-parse-errors
     :modes '(lean4-mode))
   (add-to-list 'flycheck-checkers 'lean4-checker))
diff --git a/src/library/module_mgr.h b/src/library/module_mgr.h
index 3184714e68..3d5edbecc8 100644
--- a/src/library/module_mgr.h
+++ b/src/library/module_mgr.h
@@ -55,8 +55,6 @@ class module_mgr {
 
     time_t build_module(module_name const & mod, bool can_use_olean, name_set module_stack);
 
-    std::vector<module_name>
-    get_direct_imports(std::string const & file_name, std::string const & contents);
     time_t build_lean(std::shared_ptr<module_info> const & mod, name_set const & module_stack);
 public:
     module_mgr(search_path const & path,
@@ -65,6 +63,7 @@ public:
 
     std::shared_ptr<module_info const> get_module(module_name const &);
     module_loader mk_loader();
+    std::vector<module_name> get_direct_imports(std::string const & file_name, std::string const & contents);
 
     void set_save_olean(bool save_olean) { m_save_olean = save_olean; }
 
diff --git a/src/shell/lean.cpp b/src/shell/lean.cpp
index 27a2f33dc4..105be54fbb 100644
--- a/src/shell/lean.cpp
+++ b/src/shell/lean.cpp
@@ -178,6 +178,7 @@ static void display_help(std::ostream & out) {
     std::cout << "  --githash          display the git commit hash number used to build this binary\n";
     std::cout << "  --run              executes the 'main' definition\n";
     std::cout << "  --make             create olean files\n";
+    std::cout << "  --stdin            interpret stdin as content of single .lean file\n";
     std::cout << "  --recursive        recursively find *.lean files in directory arguments\n";
     std::cout << "  --trust=num -t     trust level (default: max) 0 means do not trust any macro,\n"
               << "                     and type check all imported modules\n";
@@ -210,6 +211,7 @@ static struct option g_long_options[] = {
     {"help",         no_argument,       0, 'h'},
     {"githash",      no_argument,       0, 'g'},
     {"make",         no_argument,       0, 'm'},
+    {"stdin",        no_argument,       0, 'i'},
     {"recursive",    no_argument,       0, 'R'},
     {"memory",       required_argument, 0, 'M'},
     {"trust",        required_argument, 0, 't'},
@@ -310,6 +312,7 @@ int main(int argc, char ** argv) {
 #endif
     ::initializer init;
     bool make_mode          = false;
+    bool use_stdin          = false;
     bool recursive          = false;
     unsigned trust_lvl      = LEAN_BELIEVER_TRUST_LEVEL+1;
     bool test_suite         = false;
@@ -346,6 +349,9 @@ int main(int argc, char ** argv) {
         case 's':
             lean::lthread::set_thread_stack_size(static_cast<size_t>((atoi(optarg)/4)*4)*static_cast<size_t>(1024));
             break;
+        case 'i':
+            use_stdin = true;
+            break;
         case 'm':
             make_mode = true;
             recursive = true;
@@ -413,6 +419,9 @@ int main(int argc, char ** argv) {
         }
     }
 
+    if (use_stdin)
+        recursive = false;
+
     if (auto max_memory = opts.get_unsigned(get_max_memory_opt_name(),
                                             opts.get_bool("server") ? LEAN_SERVER_DEFAULT_MAX_MEMORY : LEAN_DEFAULT_MAX_MEMORY)) {
         set_max_memory_megabyte(max_memory);
@@ -467,6 +476,40 @@ int main(int argc, char ** argv) {
             mods.push_back({mod, mod_info});
         }
 
+        bool ok = true;
+
+        if (use_stdin) {
+            std::stringstream buf;
+            buf << std::cin.rdbuf();
+
+            // This is where we will later spin off the server
+            scope_global_ios scope_ios(ios);
+            scope_traces_as_messages scope_trace_msgs("<stdin>", {1, 0});
+            message_log l;
+            scope_message_log scope_log(l);
+            auto imports = mod_mgr.get_direct_imports("<stdin>", buf.str());
+            for (auto & d : imports) {
+                mod_mgr.get_module(d);
+            }
+
+            auto mod_env = import_modules(env, imports, mod_mgr.mk_loader());
+            parser p(mod_env, ios, buf, "<stdin>");
+            // The server will obviously do something more complicated from here
+            p.parse_commands();
+
+            for (auto const & msg : l.to_buffer()) {
+                if (json_output) {
+#if defined(LEAN_JSON)
+                    print_json(std::cout, msg);
+#endif
+                } else {
+                    std::cout << msg;
+                }
+            }
+            if (l.has_errors())
+                ok = false;
+        }
+
         for (auto & mod : mods) {
             if (test_suite) {
                 std::ofstream out(mod.m_file_name + ".test_suite.out");
@@ -482,7 +525,6 @@ int main(int argc, char ** argv) {
 
         display_cumulative_profiling_times(std::cerr);
 
-        bool ok = true;
         if (!test_suite) {
             for (auto & mod : mods) {
                 for (auto const & msg : mod.m_mod_info->m_log.to_buffer()) {