diff --git a/clients/tui/nm-editor-bindings.c b/clients/tui/nm-editor-bindings.c
index 3753aaa9ac..7ac7f0c7e2 100644
--- a/clients/tui/nm-editor-bindings.c
+++ b/clients/tui/nm-editor-bindings.c
@@ -70,45 +70,6 @@ nm_editor_bindings_init (void)
 	g_value_register_transform_func (G_TYPE_STRING, G_TYPE_UINT, value_transform_string_uint);
 }
 
-static gboolean
-parse_addr_prefix (const char  *text,
-                   int          family,
-                   char       **addr,
-                   guint32     *prefix)
-{
-	const char *slash;
-	char *addrstr, *end;
-	gboolean valid;
-
-	slash = strchr (text, '/');
-
-	if (slash)
-		addrstr = g_strndup (text, slash - text);
-	else
-		addrstr = g_strdup (text);
-	valid = nm_utils_ipaddr_valid (family, addrstr);
-
-	if (slash) {
-		*prefix = strtoul (slash + 1, &end, 10);
-		if (   *end
-		    || *prefix == 0
-		    || (family == AF_INET && *prefix > 32)
-		    || (family == AF_INET6 && *prefix > 128))
-			valid = FALSE;
-	} else if (prefix) {
-		if (family == AF_INET)
-			*prefix = 32;
-		else
-			*prefix = 128;
-	}
-
-	if (addr && valid)
-		*addr = addrstr;
-	else
-		g_free (addrstr);
-	return valid;
-}
-
 static gboolean
 ip_addresses_with_prefix_to_strv (GBinding     *binding,
                                   const GValue *source_value,
@@ -151,7 +112,7 @@ ip_addresses_with_prefix_from_strv (GBinding     *binding,
 	GPtrArray *addrs;
 	NMIPAddress *addr;
 	char *addrstr;
-	guint32 prefix;
+	int prefix;
 	int i;
 
 	strings = g_value_get_boxed (source_value);
@@ -170,11 +131,24 @@ ip_addresses_with_prefix_from_strv (GBinding     *binding,
 		} else
 			addr = addrs->pdata[i];
 
-		if (!parse_addr_prefix (strings[i], family, &addrstr, &prefix)) {
+		if (!nm_utils_parse_inaddr_prefix (strings[i], family, &addrstr, &prefix)) {
 			g_ptr_array_unref (addrs);
 			return FALSE;
 		}
 
+		if (prefix == -1) {
+			if (family == AF_INET) {
+				in_addr_t v4;
+
+				inet_pton (family, addrstr, &v4);
+				if (nm_utils_ip_is_site_local (AF_INET, &v4))
+					prefix = nm_utils_ip4_get_default_prefix (v4);
+				else
+					prefix = 32;
+			} else
+				prefix = 64;
+		}
+
 		nm_ip_address_set_address (addr, addrstr);
 		nm_ip_address_set_prefix (addr, prefix);
 		g_free (addrstr);
@@ -451,10 +425,10 @@ ip_route_transform_from_dest_string (GBinding     *binding,
 	NMIPRoute *route;
 	const char *text;
 	char *addrstr;
-	guint32 prefix;
+	int prefix;
 
 	text = g_value_get_string (source_value);
-	if (!parse_addr_prefix (text, family, &addrstr, &prefix))
+	if (!nm_utils_parse_inaddr_prefix (text, family, &addrstr, &prefix))
 		return FALSE;
 
 	/* Fetch the original property value */
@@ -462,6 +436,21 @@ ip_route_transform_from_dest_string (GBinding     *binding,
 	              g_binding_get_source_property (binding), &route,
 	              NULL);
 
+	if (prefix == -1) {
+		if (family == AF_INET) {
+			in_addr_t v4;
+
+			inet_pton (family, addrstr, &v4);
+			if (nm_utils_ip_is_site_local (AF_INET, &v4)) {
+				prefix = nm_utils_ip4_get_default_prefix (v4);
+				if (v4 & (~nm_utils_ip4_prefix_to_netmask (prefix)))
+					prefix = 32;
+			} else
+				prefix = 32;
+		} else
+			prefix = 64;
+	}
+
 	nm_ip_route_set_dest (route, addrstr);
 	nm_ip_route_set_prefix (route, prefix);
 	g_free (addrstr);
diff --git a/clients/tui/nmt-ip-entry.c b/clients/tui/nmt-ip-entry.c
index 8d8f888f0d..1556c8d7fe 100644
--- a/clients/tui/nmt-ip-entry.c
+++ b/clients/tui/nmt-ip-entry.c
@@ -123,39 +123,12 @@ ip_entry_validate (NmtNewtEntry *entry,
                    gpointer      user_data)
 {
 	NmtIPEntryPrivate *priv = NMT_IP_ENTRY_GET_PRIVATE (entry);
-	guchar buf[16];
-	guint32 prefix;
-	const char *slash;
-	char *addrstr, *end;
-	gboolean valid;
 
 	if (!*text)
 		return priv->optional;
-
-	slash = strchr (text, '/');
-
-	if (slash) {
-		if (!priv->prefix)
-			return FALSE;
-		addrstr = g_strndup (text, slash - text);
-	} else
-		addrstr = g_strdup (text);
-	valid = (inet_pton (priv->family, addrstr, buf) == 1);
-	g_free (addrstr);
-
-	if (!valid)
-		return FALSE;
-
-	if (slash) {
-		prefix = strtoul (slash + 1, &end, 10);
-		if (   *end
-		    || prefix == 0
-		    || (priv->family == AF_INET && prefix > 32)
-		    || (priv->family == AF_INET6 && prefix > 128))
-			valid = FALSE;
-	}
-
-	return valid;
+	if (priv->prefix)
+		return nm_utils_parse_inaddr_prefix (text, priv->family, NULL, NULL);
+	return nm_utils_parse_inaddr (text, priv->family, NULL);
 }
 
 static void
diff --git a/shared/nm-utils/nm-shared-utils.c b/shared/nm-utils/nm-shared-utils.c
index aa1e9f02dd..b512e52a57 100644
--- a/shared/nm-utils/nm-shared-utils.c
+++ b/shared/nm-utils/nm-shared-utils.c
@@ -169,6 +169,79 @@ nm_utils_ip_is_site_local (int addr_family,
 
 /*****************************************************************************/
 
+gboolean
+nm_utils_parse_inaddr (const char *text,
+                       int family,
+                       char **out_addr)
+{
+	union {
+		in_addr_t v4;
+		struct in6_addr v6;
+	} addrbin;
+	char addrstr_buf[MAX (INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
+
+	g_return_val_if_fail (text, FALSE);
+
+	if (family == AF_UNSPEC)
+		family = strchr (text, ':') ? AF_INET6 : AF_INET;
+	else
+		g_return_val_if_fail (NM_IN_SET (family, AF_INET, AF_INET6), FALSE);
+
+	if (inet_pton (family, text, &addrbin) != 1)
+		return FALSE;
+
+	NM_SET_OUT (out_addr, g_strdup (inet_ntop (family, &addrbin, addrstr_buf, sizeof (addrstr_buf))));
+	return TRUE;
+}
+
+gboolean
+nm_utils_parse_inaddr_prefix (const char *text,
+                              int family,
+                              char **out_addr,
+                              int *out_prefix)
+{
+	gs_free char *addrstr_free = NULL;
+	int prefix = -1;
+	const char *slash;
+	const char *addrstr;
+	union {
+		in_addr_t v4;
+		struct in6_addr v6;
+	} addrbin;
+	char addrstr_buf[MAX (INET_ADDRSTRLEN, INET6_ADDRSTRLEN)];
+
+	g_return_val_if_fail (text, FALSE);
+
+	if (family == AF_UNSPEC)
+		family = strchr (text, ':') ? AF_INET6 : AF_INET;
+	else
+		g_return_val_if_fail (NM_IN_SET (family, AF_INET, AF_INET6), FALSE);
+
+	slash = strchr (text, '/');
+	if (slash)
+		addrstr = addrstr_free = g_strndup (text, slash - text);
+	else
+		addrstr = text;
+
+	if (inet_pton (family, addrstr, &addrbin) != 1)
+		return FALSE;
+
+	if (slash) {
+		prefix = _nm_utils_ascii_str_to_int64 (slash + 1, 10,
+		                                       0,
+		                                       family == AF_INET ? 32 : 128,
+		                                       -1);
+		if (prefix == -1)
+			return FALSE;
+	}
+
+	NM_SET_OUT (out_addr, g_strdup (inet_ntop (family, &addrbin, addrstr_buf, sizeof (addrstr_buf))));
+	NM_SET_OUT (out_prefix, prefix);
+	return TRUE;
+}
+
+/*****************************************************************************/
+
 /* _nm_utils_ascii_str_to_int64:
  *
  * A wrapper for g_ascii_strtoll, that checks whether the whole string
diff --git a/shared/nm-utils/nm-shared-utils.h b/shared/nm-utils/nm-shared-utils.h
index 968f709ade..dc17fb269f 100644
--- a/shared/nm-utils/nm-shared-utils.h
+++ b/shared/nm-utils/nm-shared-utils.h
@@ -151,6 +151,15 @@ gboolean nm_utils_ip_is_site_local (int addr_family,
 
 /*****************************************************************************/
 
+gboolean nm_utils_parse_inaddr (const char *text,
+                                int family,
+                                char **out_addr);
+
+gboolean nm_utils_parse_inaddr_prefix (const char *text,
+                                       int family,
+                                       char **out_addr,
+                                       int *out_prefix);
+
 gint64 _nm_utils_ascii_str_to_int64 (const char *str, guint base, gint64 min, gint64 max, gint64 fallback);
 
 gint _nm_utils_ascii_str_to_bool (const char *str,