diff --git a/src/shell/lean.cpp b/src/shell/lean.cpp
index 9eca80e33..cd275edfd 100644
--- a/src/shell/lean.cpp
+++ b/src/shell/lean.cpp
@@ -188,7 +188,18 @@ options set_config_option(options const & opts, char const * in) {
     }
 }
 
+
+// Auxiliary object for disabling script_state recycling when
+// its destructor is invoked
+struct disable_script_state_recycling {
+    ~disable_script_state_recycling() {
+        lean::enable_script_state_recycling(false);
+    }
+};
+
+
 int main(int argc, char ** argv) {
+    disable_script_state_recycling at_end;
     lean::save_stack_info();
     lean::init_default_print_fn();
     lean::register_modules();
diff --git a/src/util/thread_script_state.cpp b/src/util/thread_script_state.cpp
index c2bf6ab19..089ad45d7 100644
--- a/src/util/thread_script_state.cpp
+++ b/src/util/thread_script_state.cpp
@@ -8,79 +8,66 @@ Author: Leonardo de Moura
 #include <utility>
 #include <string>
 #include <memory>
+#include <iostream>
 #include "util/thread.h"
 #include "util/pair.h"
 #include "util/script_state.h"
 
 namespace lean {
-struct script_state_manager {
-    mutex g_code_mutex;
-    std::vector<pair<bool, std::string>> g_code;
-    mutex g_state_mutex;
-    std::vector<script_state> g_states;
-    std::vector<script_state> g_available_states;
-};
-
-static script_state_manager & get_manager() {
-    static std::unique_ptr<script_state_manager> g_manager;
-    if (!g_manager.get())
-        g_manager.reset(new script_state_manager());
-    return *g_manager;
-}
-
-static script_state_manager & g_aux = get_manager(); // force manager to be initialized at startup
+mutex g_code_mutex;
+std::vector<pair<bool, std::string>> g_code;
+mutex g_state_mutex;
+std::vector<script_state> g_states;
+std::vector<script_state> g_available_states;
 
 /** \brief Execute \c code in all states in the pool */
 void system_dostring(char const * code) {
-    script_state_manager & m = get_manager();
     {
         // Execute code in all existing states
-        lock_guard<mutex> lk(m.g_state_mutex);
-        for (auto & s : m.g_states) {
+        lock_guard<mutex> lk(g_state_mutex);
+        for (auto & s : g_states) {
             s.dostring(code);
         }
     }
     {
         // Save code for future states
-        lock_guard<mutex> lk(m.g_code_mutex);
-        m.g_code.push_back(mk_pair(true, code));
+        lock_guard<mutex> lk(g_code_mutex);
+        g_code.push_back(mk_pair(true, code));
     }
 }
 
 /** \brief Import \c fname in all states in the pool */
 void system_import(char const * fname) {
-    script_state_manager & m = get_manager();
     {
         // Import file in all existing states
-        lock_guard<mutex> lk(m.g_state_mutex);
-        for (auto & s : m.g_states) {
+        lock_guard<mutex> lk(g_state_mutex);
+        for (auto & s : g_states) {
             s.import_explicit(fname);
         }
     }
     {
         // Save module for future states
-        lock_guard<mutex> lk(m.g_code_mutex);
-        m.g_code.push_back(mk_pair(false, fname));
+        lock_guard<mutex> lk(g_code_mutex);
+        g_code.push_back(mk_pair(false, fname));
     }
 }
 
 static script_state get_state() {
-    script_state_manager & m = get_manager();
     {
         // Try to reuse existing state
-        lock_guard<mutex> lk(m.g_state_mutex);
-        if (!m.g_available_states.empty()) {
-            script_state r(m.g_available_states.back());
-            m.g_available_states.pop_back();
+        lock_guard<mutex> lk(g_state_mutex);
+        if (!g_available_states.empty()) {
+            script_state r(g_available_states.back());
+            g_available_states.pop_back();
             return r;
         }
     }
 
     {
         // Execute existing code in new state
-        lock_guard<mutex> lk(m.g_code_mutex);
+        lock_guard<mutex> lk(g_code_mutex);
         script_state r;
-        for (auto const & p : m.g_code) {
+        for (auto const & p : g_code) {
             if (p.first)
                 r.dostring(p.second.c_str());
             else
@@ -88,17 +75,24 @@ static script_state get_state() {
         }
         {
             // save new state in vector of all states
-            lock_guard<mutex> lk(m.g_state_mutex);
-            m.g_states.push_back(r);
+            lock_guard<mutex> lk(g_state_mutex);
+            g_states.push_back(r);
         }
         return r;
     }
 }
 
+static bool g_recycle_state = true;
+
+void enable_script_state_recycling(bool flag) {
+    g_recycle_state = flag;
+}
+
 static void recycle_state(script_state s) {
-    script_state_manager & m = get_manager();
-    lock_guard<mutex> lk(m.g_state_mutex);
-    m.g_available_states.push_back(s);
+    if (g_recycle_state) {
+        lock_guard<mutex> lk(g_state_mutex);
+	g_available_states.push_back(s);
+    }
 }
 
 struct script_state_ref {
diff --git a/src/util/thread_script_state.h b/src/util/thread_script_state.h
index df735e7ca..e3c54b7fe 100644
--- a/src/util/thread_script_state.h
+++ b/src/util/thread_script_state.h
@@ -38,4 +38,6 @@ script_state get_thread_script_state();
    and available for other threads.
 */
 void release_thread_script_state();
+
+void enable_script_state_recycling(bool flag);
 }