diff -uNrp bogofilter-1.2.2.base64/src/iconvert.c bogofilter-1.2.2/src/iconvert.c
--- bogofilter-1.2.2.base64/src/iconvert.c	2010-03-14 20:08:11.000000000 -0400
+++ bogofilter-1.2.2/src/iconvert.c	2012-12-13 10:06:56.603529996 -0500
@@ -76,7 +76,7 @@ static void convert(iconv_t xd, buff_t *
 	outbuf = (char *)dst->t.u.text + dst->t.leng;
 	outbytesleft = dst->size - dst->read - dst->t.leng;
 
-	if (outbytesleft == 0)
+	if (outbytesleft <= 0)
 	    break;
 
 	/*
@@ -141,6 +141,10 @@ static void convert(iconv_t xd, buff_t *
 	    switch (err) {
 	    case EILSEQ:		/* invalid multibyte sequence */
 	    case EINVAL:		/* incomplete multibyte sequence */
+		if(outbytesleft <= 0) {
+                    done = true;
+                    break;
+		}
 		/* copy 1 byte (or substitute a '?') */
 		if (!replace_nonascii_characters)
 		    *outbuf = *inbuf;
diff -uNrp bogofilter-1.2.2.base64/src/tests/Makefile.am bogofilter-1.2.2/src/tests/Makefile.am
--- bogofilter-1.2.2.base64/src/tests/Makefile.am	2010-07-05 07:26:36.000000000 -0400
+++ bogofilter-1.2.2/src/tests/Makefile.am	2012-12-13 10:07:07.893536640 -0500
@@ -45,6 +45,7 @@ PARSING_TESTS = \
 	t.multiple.tokens.head t.multiple.tokens.body t.multiple.tokens.min.mul \
 	$(ENCODING_TESTS) \
 	t.rfc2047_broken t.rfc2047_folded \
+	t.crash-invalid-base64 \
 	t.message_addr t.message_id t.queue_id
 
 WORDLIST_TESTS = t.dump.load t.nonascii.replace t.maint t.robx t.regtest t.upgrade.subnet.prefix t.multiple.wordlists t.probe t.bf_compact
diff -uNrp bogofilter-1.2.2.base64/src/tests/t.crash-invalid-base64 bogofilter-1.2.2/src/tests/t.crash-invalid-base64
--- bogofilter-1.2.2.base64/src/tests/t.crash-invalid-base64	1969-12-31 19:00:00.000000000 -0500
+++ bogofilter-1.2.2/src/tests/t.crash-invalid-base64	2012-12-13 10:07:23.733544561 -0500
@@ -0,0 +1,21 @@
+#! /bin/sh
+
+. ${srcdir:=.}/t.frame
+
+# make sure that we do not crash on excessively long tokens
+# Test program by Julius Plenz, TU Berlin.
+perl -e '
+print <<EOF
+Content-Type: multipart/mixed;boundary="----=_20121014031204_57463"
+
+------=_20121014031204_57463
+Content-Type: text/plain; charset="utf-8"
+
+------=_20121014031204_57463
+Content-Transfer-Encoding: base64
+
+EOF
+;
+print(("vfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvfvf\n")x600);
+print "------=_20121014031204_57463--";' \
+| $VAL $BOGOFILTER -p -e -C > /dev/null