diff --git a/src/psl.c b/src/psl.c
index f3b2156..f13bceb 100644
--- a/src/psl.c
+++ b/src/psl.c
@@ -704,10 +704,14 @@ static int _psl_idna_toASCII(_psl_idna_t *idna _UNUSED, const char *utf8, char *
 #if IDN2_VERSION_NUMBER >= 0x00140000
 	int rc;
 
-	/* IDN2_TRANSITIONAL automatically converts to lowercase */
-	/* IDN2_NFC_INPUT converts to NFC before toASCII conversion */
+	/* IDN2_TRANSITIONAL automatically converts to lowercase
+	 * IDN2_NFC_INPUT converts to NFC before toASCII conversion
+	 * Since IDN2_TRANSITIONAL implicitely does NFC conversion, we don't need
+	 * the additional IDN2_NFC_INPUT. But just for the unlikely case that the linked
+	 * library is not matching the headers when building and it doesn't support TR46,
+	 * we provide IDN2_NFC_INPUT. */
 
-	if ((rc = idn2_lookup_u8((uint8_t *)utf8, (uint8_t **)ascii, IDN2_NFC_INPUT | IDN2_TRANSITIONAL)) == IDN2_OK)
+	if ((rc = idn2_lookup_u8((uint8_t *)utf8, (uint8_t **)ascii, IDN2_NFC_INPUT | IDN2_NONTRANSITIONAL)) == IDN2_OK)
 		ret = 0;
 	/* else
 		fprintf(stderr, "toASCII(%s) failed (%d): %s\n", lower, rc, idn2_strerror(rc)); */