diff --git a/third_party/pffft/generate_seed_corpus.py b/third_party/pffft/generate_seed_corpus.py
index c48aa871188797..652d7a88202500 100755
--- a/third_party/pffft/generate_seed_corpus.py
+++ b/third_party/pffft/generate_seed_corpus.py
@@ -11,7 +11,7 @@
 import random
 import sys
 
-MAX_INPUT_SIZE = int(1e6)
+MAX_INPUT_SIZE = 5000  # < 1 MB so we don't blow up fuzzer build sizes.
 MAX_FLOAT32 = 3.4028235e+38