diff --git a/m-string.h b/m-string.h
index 09ef4d6e..c23c8c22 100644
--- a/m-string.h
+++ b/m-string.h
@@ -909,6 +909,7 @@ namespace m_string {
    EXT_ALGO(STRING_SPLIT)                                               \
    )
 
+#define M_OPL_string_t() STRING_OPLIST
 
 /* Macro encapsulation to give default value for start offset */
 #define string_search_char(v, ...)					\
diff --git a/tests/test-mstring.c b/tests/test-mstring.c
index 5f87c76b..32f879d0 100644
--- a/tests/test-mstring.c
+++ b/tests/test-mstring.c
@@ -24,6 +24,15 @@
 #define STRING_WITHIN_TEST
 #include "m-string.h"
 
+static void test1(void)
+{
+  M_LET(s1, s2, string_t) {
+    string_set_str(s1, "Success!");
+    string_set(s2, s1);
+  }
+}
+
+
 int main(void)
 {
   string_t s1;