diff --git a/psycopg/adapter_qstring.c b/psycopg/adapter_qstring.c
index eca42182..febb49ac 100644
--- a/psycopg/adapter_qstring.c
+++ b/psycopg/adapter_qstring.c
@@ -178,7 +178,7 @@ qstring_set_encoding(qstringObject *self, PyObject *pyenc)
     Py_INCREF(pyenc);
     if (!(pyenc = psycopg_ensure_bytes(pyenc))) { goto exit; }
     if (!(tmp = Bytes_AsString(pyenc))) { goto exit; }
-    if (0 > psycopg_strdup(&cenc, tmp, 0)) { goto exit; }
+    if (0 > psycopg_strdup(&cenc, tmp, -1)) { goto exit; }
 
     Dprintf("qstring_set_encoding: encoding set to %s", cenc);
     PyMem_Free((void *)self->encoding);
diff --git a/psycopg/connection_type.c b/psycopg/connection_type.c
index d22ceb97..ba4e4335 100644
--- a/psycopg/connection_type.c
+++ b/psycopg/connection_type.c
@@ -1097,7 +1097,7 @@ connection_setup(connectionObject *self, const char *dsn, long int async)
             self, async, Py_REFCNT(self)
       );
 
-    if (0 > psycopg_strdup(&self->dsn, dsn, 0)) { goto exit; }
+    if (0 > psycopg_strdup(&self->dsn, dsn, -1)) { goto exit; }
     if (!(self->notice_list = PyList_New(0))) { goto exit; }
     if (!(self->notifies = PyList_New(0))) { goto exit; }
     self->async = async;
diff --git a/psycopg/cursor_type.c b/psycopg/cursor_type.c
index b2aef3df..c580daa2 100644
--- a/psycopg/cursor_type.c
+++ b/psycopg/cursor_type.c
@@ -1079,7 +1079,7 @@ psyco_curs_callproc(cursorObject *self, PyObject *args)
             if (!(cpname = Bytes_AsString(pname))) { goto exit; }
 
             if (!(scpnames[i] = psycopg_escape_identifier(
-                    self->conn, cpname, 0))) {
+                    self->conn, cpname, -1))) {
                 Py_CLEAR(pname);
                 goto exit;
             }
@@ -1457,12 +1457,12 @@ psyco_curs_copy_from(cursorObject *self, PyObject *args, PyObject *kwargs)
         goto exit;
 
     if (!(quoted_delimiter = psycopg_escape_string(
-            self->conn, sep, 0, NULL, NULL))) {
+            self->conn, sep, -1, NULL, NULL))) {
         goto exit;
     }
 
     if (!(quoted_null = psycopg_escape_string(
-            self->conn, null, 0, NULL, NULL))) {
+            self->conn, null, -1, NULL, NULL))) {
         goto exit;
     }
 
@@ -1551,12 +1551,12 @@ psyco_curs_copy_to(cursorObject *self, PyObject *args, PyObject *kwargs)
         goto exit;
 
     if (!(quoted_delimiter = psycopg_escape_string(
-            self->conn, sep, 0, NULL, NULL))) {
+            self->conn, sep, -1, NULL, NULL))) {
         goto exit;
     }
 
     if (!(quoted_null = psycopg_escape_string(
-            self->conn, null, 0, NULL, NULL))) {
+            self->conn, null, -1, NULL, NULL))) {
         goto exit;
     }
 
@@ -1899,10 +1899,10 @@ cursor_setup(cursorObject *self, connectionObject *conn, const char *name)
     Dprintf("cursor_setup: parameters: name = %s, conn = %p", name, conn);
 
     if (name) {
-        if (0 > psycopg_strdup(&self->name, name, 0)) {
+        if (0 > psycopg_strdup(&self->name, name, -1)) {
             return -1;
         }
-        if (!(self->qname = psycopg_escape_identifier(conn, name, 0))) {
+        if (!(self->qname = psycopg_escape_identifier(conn, name, -1))) {
             return -1;
         }
     }
diff --git a/psycopg/pqpath.c b/psycopg/pqpath.c
index 9dbd489a..c8d9c46b 100644
--- a/psycopg/pqpath.c
+++ b/psycopg/pqpath.c
@@ -227,7 +227,7 @@ pq_raise(connectionObject *conn, cursorObject *curs, PGresult **pgres)
         errorObject *perr = (errorObject *)pyerr;
 
         PyMem_Free(perr->pyenc);
-        psycopg_strdup(&perr->pyenc, conn->pyenc, 0);
+        psycopg_strdup(&perr->pyenc, conn->pyenc, -1);
 
         Py_CLEAR(perr->pgerror);
         perr->pgerror = error_text_from_chars(perr, err);
@@ -765,7 +765,7 @@ pq_tpc_command_locked(connectionObject *conn, const char *cmd, const char *tid,
     PyEval_RestoreThread(*tstate);
 
     /* convert the xid into the postgres transaction_id and quote it. */
-    if (!(etid = psycopg_escape_string(conn, tid, 0, NULL, NULL)))
+    if (!(etid = psycopg_escape_string(conn, tid, -1, NULL, NULL)))
     { goto exit; }
 
     /* prepare the command to the server */
diff --git a/psycopg/psycopg.h b/psycopg/psycopg.h
index 438d7636..fc5b533e 100644
--- a/psycopg/psycopg.h
+++ b/psycopg/psycopg.h
@@ -129,7 +129,7 @@ RAISES HIDDEN PyObject *psyco_set_error(PyObject *exc, cursorObject *curs, const
 HIDDEN char *psycopg_escape_string(connectionObject *conn,
               const char *from, Py_ssize_t len, char *to, Py_ssize_t *tolen);
 HIDDEN char *psycopg_escape_identifier(connectionObject *conn,
-              const char *str, size_t len);
+              const char *str, Py_ssize_t len);
 HIDDEN int psycopg_strdup(char **to, const char *from, Py_ssize_t len);
 HIDDEN int psycopg_is_text_file(PyObject *f);
 
diff --git a/psycopg/psycopgmodule.c b/psycopg/psycopgmodule.c
index bf7d908a..c4d1517a 100644
--- a/psycopg/psycopgmodule.c
+++ b/psycopg/psycopgmodule.c
@@ -165,7 +165,6 @@ psyco_quote_ident(PyObject *self, PyObject *args, PyObject *kwargs)
 {
     PyObject *ident = NULL, *obj = NULL, *result = NULL;
     connectionObject *conn;
-    const char *str;
     char *quoted = NULL;
 
     static char *kwlist[] = {"ident", "scope", NULL};
@@ -188,12 +187,9 @@ psyco_quote_ident(PyObject *self, PyObject *args, PyObject *kwargs)
     Py_INCREF(ident); /* for ensure_bytes */
     if (!(ident = psycopg_ensure_bytes(ident))) { goto exit; }
 
-    str = Bytes_AS_STRING(ident);
+    if (!(quoted = psycopg_escape_identifier(conn,
+        Bytes_AS_STRING(ident), Bytes_GET_SIZE(ident)))) { goto exit; }
 
-    quoted = psycopg_escape_identifier(conn, str, strlen(str));
-    if (!quoted) {
-        goto exit;
-    }
     result = conn_text_from_chars(conn, quoted);
 
 exit:
diff --git a/psycopg/utils.c b/psycopg/utils.c
index bc6f7bec..85ca9d6c 100644
--- a/psycopg/utils.c
+++ b/psycopg/utils.c
@@ -40,6 +40,8 @@
  * and set an exception. The returned string includes quotes and leading E if
  * needed.
  *
+ * `len` is optional: if < 0 it will be calculated.
+ *
  * If tolen is set, it will contain the length of the escaped string,
  * including quotes.
  */
@@ -50,7 +52,7 @@ psycopg_escape_string(connectionObject *conn, const char *from, Py_ssize_t len,
     Py_ssize_t ql;
     int eq = (conn && (conn->equote)) ? 1 : 0;
 
-    if (len == 0) {
+    if (len < 0) {
         len = strlen(from);
     } else if (strchr(from, '\0') != from + len) {
         PyErr_Format(PyExc_ValueError, "A string literal cannot contain NUL (0x00) characters.");
@@ -92,13 +94,13 @@ psycopg_escape_string(connectionObject *conn, const char *from, Py_ssize_t len,
 
 /* Escape a string for inclusion in a query as identifier.
  *
- * 'len' is optional: if 0 the length is calculated.
+ * 'len' is optional: if < 0 it will be calculated.
  *
  * Return a string allocated by Postgres: free it using PQfreemem
  * In case of error set a Python exception.
  */
 char *
-psycopg_escape_identifier(connectionObject *conn, const char *str, size_t len)
+psycopg_escape_identifier(connectionObject *conn, const char *str, Py_ssize_t len)
 {
     char *rv = NULL;
 
@@ -107,7 +109,7 @@ psycopg_escape_identifier(connectionObject *conn, const char *str, size_t len)
         goto exit;
     }
 
-    if (!len) { len = strlen(str); }
+    if (len < 0) { len = strlen(str); }
 
     rv = PQescapeIdentifier(conn->pgconn, str, len);
     if (!rv) {
@@ -127,7 +129,7 @@ exit:
 /* Duplicate a string.
  *
  * Allocate a new buffer on the Python heap containing the new string.
- * 'len' is optional: if 0 the length is calculated.
+ * 'len' is optional: if < 0 the length is calculated.
  *
  * Store the return in 'to' and return 0 in case of success, else return -1
  * and raise an exception.
@@ -141,7 +143,7 @@ psycopg_strdup(char **to, const char *from, Py_ssize_t len)
         *to = NULL;
         return 0;
     }
-    if (!len) { len = strlen(from); }
+    if (len < 0) { len = strlen(from); }
     if (!(*to = PyMem_Malloc(len + 1))) {
         PyErr_NoMemory();
         return -1;