diff --git a/tests/Makefile b/tests/Makefile
index 3d2ebe3f..39d8d068 100644
--- a/tests/Makefile
+++ b/tests/Makefile
@@ -164,6 +164,7 @@ SYNTHESIS_DATA=	M-ALGO test-malgo.c.c test-malgo.synt			\
 		M-FUNCOBJ test-mfuncobj.c.c test-mfuncobj.synt			\
 		M-GENINT ../m-genint.h test-mgenint.synt				\
 		M-I-LIST test-milist.c.c test-milist.synt				\
+		M-I-SHARED test-mishared.c.c test-mishared.synt			\
 		M-LIST test-mlist.c.c test-mlist.synt					\
 		M-MEMPOOL test-mmempool.c.c test-mmempool.synt			\
 		M-MUTEX ../m-mutex.h test-mmutex.synt					\
diff --git a/tests/test-mishared.c b/tests/test-mishared.c
new file mode 100644
index 00000000..ee7eeae5
--- /dev/null
+++ b/tests/test-mishared.c
@@ -0,0 +1,142 @@
+/*
+ * Copyright (c) 2017-2020, Patrick Pelissier
+ * All rights reserved.
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ * + Redistributions of source code must retain the above copyright
+ *   notice, this list of conditions and the following disclaimer.
+ * + Redistributions in binary form must reproduce the above copyright
+ *   notice, this list of conditions and the following disclaimer in the
+ *   documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND ANY
+ * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ * DISCLAIMED. IN NO EVENT SHALL THE REGENTS AND CONTRIBUTORS BE LIABLE FOR ANY
+ * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+ * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+ * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+#include <assert.h>
+#include "test-obj.h"
+
+#include "m-i-shared.h"
+
+#include "m-mutex.h"
+#include "coverage.h"
+
+typedef struct ishared_s {
+    ISHARED_PTR_INTERFACE(ishared1, struct ishared_s);
+    ISHARED_PTR_INTERFACE(ishared2, struct ishared_s);
+    int data[100];
+} ishared_t[1];
+
+static void ishared_init_data(struct ishared_s *x)
+{
+    for(int i = 0 ; i < 100; i++)
+        x->data[i] = i * i;
+}
+
+static void ishared_test(struct ishared_s *x)
+{
+    for(int i = 0 ; i < 100; i++) {
+        assert (x->data[i] == i*i);
+    }
+}
+
+START_COVERAGE
+ISHARED_PTR_DEF(ishared1, struct ishared_s, (INIT(API_2(ishared_init_data))))
+ISHARED_PTR_DEF(ishared2, struct ishared_s, (INIT(API_2(ishared_init_data)), NEW(0), DEL(0)) )
+END_COVERAGE
+
+/*ISHARED_PTR_DEF_AS(SharedDouble, SharedDouble, double) */
+
+static void test_single(void)
+{
+    ishared1_t p1, p2;
+    p1 = ishared1_init_new();
+    ishared_test(p1);
+    p2 = ishared1_init_set(p1);
+    ishared_test(p2);
+    ishared1_clear(p1);
+    ishared_test(p2);
+
+    p1 = ishared1_init(NULL);
+    ishared1_set(&p1, p2);
+    ishared1_clean(&p2);
+    assert(p2 == NULL);
+    ishared_test(p1);
+    ishared1_clear(p1);
+
+    p1 = ishared1_init_set(p2);
+    assert(p1 == NULL);
+    ishared1_clear(p1);
+
+    ishared1_clear(p2);
+
+    struct ishared_s *x = malloc(sizeof (struct ishared_s));
+    assert(x != NULL);
+    ishared_init_data(x);
+    p1 = ishared1_init(x);
+    ishared_test(p1);
+    ishared1_clear(p1);
+}
+
+static struct ishared_s g_var = {ISHARED_PTR_STATIC_INIT(ishared2, struct ishared_s) };
+
+static void test_static(void)
+{
+    ishared2_t p1, p2;
+
+    p1 = ishared2_init_once(NULL);
+    assert(p1 == NULL);
+    p1 = ishared2_init_once(&g_var);
+    ishared_test(p1);
+    p2 = ishared2_init_once(&g_var);
+    ishared_test(p2);
+    ishared2_clear(p1);
+    ishared_test(p2);
+    ishared2_clear(p2);
+}
+
+#define MAX_THREAD 256
+#define MAX_VAR 5
+
+#define VAL(x) { ISHARED_PTR_STATIC_INIT(ishared2, struct ishared_s) } 
+static struct ishared_s g_tab[MAX_VAR] = { 
+    M_MAP_C(VAL, M_SEQ(1, MAX_VAR))
+};
+
+static void func(void *arg)
+{
+    int id = (int)(intptr_t) arg;
+    int v  = id % MAX_VAR;
+    ishared2_t p = ishared2_init_once(&g_tab[v]);
+    for(int i = 0; i < 100; i++) {
+        ishared_test(p);
+    }
+    ishared2_clear(p);
+}
+
+static void test_shared(void)
+{
+    m_thread_t id[MAX_THREAD];
+
+    for(int i = 0; i < MAX_THREAD; i++) {
+        m_thread_create(id[i], func, (void*) (intptr_t) i);
+    }
+    for(int i = 0; i < MAX_THREAD; i++) {
+        m_thread_join(id[i]);
+    }
+}
+
+int main(void)
+{
+  test_single();
+  test_static();
+  test_shared();
+  exit(0);
+}