diff --git a/pdf.c b/pdf.c
index 7b927798e08bcae49a7db00db9851f018f37c6c1..8bddb570a22ecf29ee1a8aba17cdcccb0f233c07 100644
--- a/pdf.c
+++ b/pdf.c
@@ -893,7 +893,11 @@ init_parser(struct Env *aux)
 	/* debug parser to consume as much as possible */
 	H_RULE(pdfdbg,	SEQ(header, h_many(tail), body, OPT(xr_td), OPT(startxr)));
 
-	/* Parser for Ascii85Decode */
+	/*
+	 * filters
+	 */
+
+	/* Ascii85Decode */
 	H_RULE(a85eod,	SEQ(h_ch('~'), OPT(h_many(lwchar)), h_ch('>')));
 	H_ARULE(a85zero,	h_ch('z'));
 	H_ARULE(a85digit,	h_ch_range('!', 'u'));
@@ -915,7 +919,7 @@ init_parser(struct Env *aux)
 
 	H_RULE(a85string,	SEQ(h_many(a85group), OPT(a85partialgroup), IGN(a85eod)));
 
-	/* AsciiHexDecode parser */
+	/* AsciiHexDecode */
 	H_RULE(ahexeod,	h_ch('>'));
 	H_RULE(hdigitpair, SEQ(IGN(OPT(h_many(lwchar))), hdigit, IGN(OPT(h_many(lwchar))), hdigit));
 	H_ARULE(ahextruncated, SEQ(IGN(OPT(h_many(lwchar))), hdigit, IGN(OPT(h_many(lwchar))), ahexeod));