diff --git a/libnm-core/nm-utils.c b/libnm-core/nm-utils.c
index e5fd8d181c..d25aa45245 100644
--- a/libnm-core/nm-utils.c
+++ b/libnm-core/nm-utils.c
@@ -2279,21 +2279,42 @@ _nm_utils_string_append_tc_parent (GString *string, const char *prefix, guint32
 guint32
 _nm_utils_parse_tc_handle (const char *str, GError **error)
 {
-	gint64 maj, min;
-	char *sep;
+	gint64 maj;
+	gint64 min = 0;
+	const char *sep;
 
-	maj = g_ascii_strtoll (str, &sep, 0x10);
-	if (*sep == ':')
-		min = g_ascii_strtoll (&sep[1], &sep, 0x10);
-	else
-		min = 0;
+	nm_assert (str);
 
-	if (*sep != '\0' || maj <= 0 || maj > 0xffff || min < 0 || min > 0xffff) {
-		g_set_error (error, 1, 0, _("'%s' is not a valid handle."), str);
-		return TC_H_UNSPEC;
+	maj = g_ascii_strtoll (str, (char **) &sep, 0x10);
+	if (sep == str)
+		goto fail;
+
+	sep = nm_str_skip_leading_spaces (sep);
+
+	if (sep[0] == ':') {
+		const char *str2 = &sep[1];
+
+		min = g_ascii_strtoll (str2, (char **) &sep, 0x10);
+		sep = nm_str_skip_leading_spaces (sep);
+		if (sep[0] != '\0')
+			goto fail;
+	} else if (sep[0] != '\0')
+		goto fail;
+
+	if (   maj <= 0
+	    || maj > 0xffff
+	    || min < 0
+	    || min > 0xffff
+	    || !NM_STRCHAR_ALL (str, ch, (   g_ascii_isxdigit (ch)
+	                                  || ch == ':'
+	                                  || g_ascii_isspace (ch)))) {
+		goto fail;
 	}
 
-	return TC_H_MAKE (maj << 16, min);
+	return TC_H_MAKE (((guint32) maj) << 16, (guint32) min);
+fail:
+	nm_utils_error_set (error, NM_UTILS_ERROR_UNKNOWN, _("'%s' is not a valid handle."), str);
+	return TC_H_UNSPEC;
 }
 
 #define TC_ATTR_SPEC_PTR(name, type, no_value, consumes_rest, str_type) \
diff --git a/libnm-core/tests/test-setting.c b/libnm-core/tests/test-setting.c
index 8bb6f04dee..5b2c323df4 100644
--- a/libnm-core/tests/test-setting.c
+++ b/libnm-core/tests/test-setting.c
@@ -3117,27 +3117,27 @@ test_parse_tc_handle (void)
 	_parse_tc_handle_inval (" ");
 	_parse_tc_handle_inval (" \n");
 	_parse_tc_handle_valid ("1", 1, 0);
-	_parse_tc_handle_inval(" 1 ");
+	_parse_tc_handle_valid(" 1 ", 1, 0);
 	_parse_tc_handle_valid ("1:", 1, 0);
-	_parse_tc_handle_inval ("1:  ");
+	_parse_tc_handle_valid ("1:  ", 1, 0);
 	_parse_tc_handle_valid ("1:0", 1, 0);
-	_parse_tc_handle_inval ("1   :0");
-	_parse_tc_handle_inval ("1   \t\n\f\r:0");
+	_parse_tc_handle_valid ("1   :0", 1, 0);
+	_parse_tc_handle_valid ("1   \t\n\f\r:0", 1, 0);
 	_parse_tc_handle_inval ("1   \t\n\f\r\v:0");
-	_parse_tc_handle_inval (" 1 : 0  ");
-	_parse_tc_handle_valid (" \t\v\n1: 0", 1, 0);
+	_parse_tc_handle_valid (" 1 : 0  ", 1, 0);
+	_parse_tc_handle_inval (" \t\v\n1: 0");
 	_parse_tc_handle_valid ("1:2", 1, 2);
 	_parse_tc_handle_valid ("01:02", 1, 2);
-	_parse_tc_handle_valid ("0x01:0x02", 1, 2);
+	_parse_tc_handle_inval ("0x01:0x02");
 	_parse_tc_handle_valid ("  01:   02", 1, 2);
 	_parse_tc_handle_valid ("019:   020", 0x19, 0x20);
 	_parse_tc_handle_valid ("FFFF:   020", 0xFFFF, 0x20);
 	_parse_tc_handle_valid ("FfFF:   ffff", 0xFFFF, 0xFFFF);
 	_parse_tc_handle_valid ("FFFF", 0xFFFF, 0);
-	_parse_tc_handle_valid ("0xFFFF", 0xFFFF, 0);
+	_parse_tc_handle_inval ("0xFFFF");
 	_parse_tc_handle_inval ("10000");
 	_parse_tc_handle_valid ("\t\n\f\r FFFF", 0xFFFF, 0);
-	_parse_tc_handle_valid ("\t\n\f\r \vFFFF", 0xFFFF, 0);
+	_parse_tc_handle_inval ("\t\n\f\r \vFFFF");
 }
 
 /*****************************************************************************/