diff --git a/lib/formats.c b/lib/formats.c
index 4a80f9e32..4e84f40d4 100644
--- a/lib/formats.c
+++ b/lib/formats.c
@@ -21,8 +21,6 @@
 
 #include "debug.h"
 
-#define RPM_ANY_CLASS 255
-
 typedef char * (*headerTagFormatFunction) (rpmtd td, char **emsg);
 
 /** \ingroup header
@@ -32,7 +30,7 @@ typedef char * (*headerTagFormatFunction) (rpmtd td, char **emsg);
 struct headerFmt_s {
     rpmtdFormats fmt;	/*!< Value of extension */
     const char *name;	/*!< Name of extension. */
-    rpmTagClass tclass;	/*!< Class of source data (RPM_ANY_CLASS for any) */
+    rpmTagClass tclass;	/*!< Class of source data (RPM_NULL_CLASS for any) */
     headerTagFormatFunction func;	/*!< Pointer to formatter function. */	
 };
 
@@ -571,9 +569,9 @@ static char *tagnumFormat(rpmtd td, char **emsg)
 
 static const struct headerFmt_s rpmHeaderFormats[] = {
     { RPMTD_FORMAT_STRING,	"string",
-	RPM_ANY_CLASS,		stringFormat },
+	RPM_NULL_CLASS,		stringFormat },
     { RPMTD_FORMAT_ARMOR,	"armor",
-	RPM_ANY_CLASS,		armorFormat },
+	RPM_NULL_CLASS,		armorFormat },
     { RPMTD_FORMAT_BASE64,	"base64",
 	RPM_BINARY_CLASS,	base64Format },
     { RPMTD_FORMAT_PGPSIG,	"pgpsig",
@@ -591,7 +589,7 @@ static const struct headerFmt_s rpmHeaderFormats[] = {
     { RPMTD_FORMAT_TRIGGERTYPE,	"triggertype",
 	RPM_NUMERIC_CLASS,	triggertypeFormat },
     { RPMTD_FORMAT_XML,		"xml",
-	RPM_ANY_CLASS,		xmlFormat },
+	RPM_NULL_CLASS,		xmlFormat },
     { RPMTD_FORMAT_OCTAL,	"octal",
 	RPM_NUMERIC_CLASS,	octalFormat },
     { RPMTD_FORMAT_HEX,		"hex",
@@ -601,9 +599,9 @@ static const struct headerFmt_s rpmHeaderFormats[] = {
     { RPMTD_FORMAT_DAY,		"day",
 	RPM_NUMERIC_CLASS,	dayFormat },
     { RPMTD_FORMAT_SHESCAPE,	"shescape",
-	RPM_ANY_CLASS,		shescapeFormat },
+	RPM_NULL_CLASS,		shescapeFormat },
     { RPMTD_FORMAT_ARRAYSIZE,	"arraysize",
-	RPM_ANY_CLASS,		arraysizeFormat },
+	RPM_NULL_CLASS,		arraysizeFormat },
     { RPMTD_FORMAT_FSTATE,	"fstate",
 	RPM_NUMERIC_CLASS,	fstateFormat },
     { RPMTD_FORMAT_VFLAGS,	"vflags",
@@ -617,12 +615,12 @@ static const struct headerFmt_s rpmHeaderFormats[] = {
     { RPMTD_FORMAT_HUMANIEC,	"humaniec",
 	RPM_NUMERIC_CLASS,	humaniecFormat },
     { RPMTD_FORMAT_TAGNAME,	"tagname",
-	RPM_ANY_CLASS,		tagnameFormat },
+	RPM_NULL_CLASS,		tagnameFormat },
     { RPMTD_FORMAT_TAGNUM,	"tagnum",
-	RPM_ANY_CLASS,		tagnumFormat },
+	RPM_NULL_CLASS,		tagnumFormat },
     { RPMTD_FORMAT_JSON,	"json",
-	RPM_ANY_CLASS,		jsonFormat },
-    { -1,			NULL, 		0,	NULL }
+	RPM_NULL_CLASS,		jsonFormat },
+    { RPMTD_FORMAT_STRING,	NULL, 		RPM_NULL_CLASS,	NULL }
 };
 
 headerFmt rpmHeaderFormatByName(const char *fmt)
@@ -652,7 +650,7 @@ char *rpmHeaderFormatCall(headerFmt fmt, rpmtd td)
     char *ret = NULL;
     char *err = NULL;
 
-    if (fmt->tclass != RPM_ANY_CLASS && rpmtdClass(td) != fmt->tclass)
+    if (fmt->tclass != RPM_NULL_CLASS && rpmtdClass(td) != fmt->tclass)
 	err = xstrdup(classEr(fmt->tclass));
     else
 	ret = fmt->func(td, &err);