diff --git a/src/test/Makefile.am b/src/test/Makefile.am
index 155e9cf..1586fa9 100644
--- a/src/test/Makefile.am
+++ b/src/test/Makefile.am
@@ -8,6 +8,12 @@ CLEANFILES = test*.log test*.trs \
 
 TESTS = test1.sh test2.sh test3.sh test4.sh test5.sh test6.sh test7.sh
 
+largesttcp.blob:
+	$(srcdir)/gen-largest-blob.py 20065 65503 $(srcdir)/largesttcp.blob
+
+largestudp.blob:
+	$(srcdir)/gen-largest-blob.py 20065 65475 $(srcdir)/largestudp.blob
+
 EXTRA_DIST = $(TESTS) \
   datafile datafile2 updatefile datafile3 datafile4 datafile5 datafile6 \
   empty.blob emptypayload.blob largesttcp.blob largestudp.blob \
diff --git a/src/test/gen-largest-blob.py b/src/test/gen-largest-blob.py
new file mode 100755
index 0000000..64399bf
--- /dev/null
+++ b/src/test/gen-largest-blob.py
@@ -0,0 +1,12 @@
+#!/usr/bin/env python3
+
+import sys
+import dns.message
+import struct
+
+m = dns.message.make_query('.', 'TYPE666')
+m.id = int(sys.argv[1])
+m.use_edns(0, options=[dns.edns.GenericOption(dns.edns.OptionType.PADDING, '\x00' * int(sys.argv[2]))])
+binary = m.to_wire(max_size=65535)
+binary = struct.pack('>H', len(binary)) + binary
+open(sys.argv[3], 'wb').write(binary)
diff --git a/src/test/largesttcp.blob b/src/test/largesttcp.blob
index 9608069..8103923 100644
Binary files a/src/test/largesttcp.blob and b/src/test/largesttcp.blob differ
diff --git a/src/test/largestudp.blob b/src/test/largestudp.blob
index cf58abd..acfd065 100644
Binary files a/src/test/largestudp.blob and b/src/test/largestudp.blob differ