diff --git a/requirements.txt b/requirements.txt
index 02be17a..eb5b0b9 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -6,4 +6,4 @@
 
 # Ply 3.6 has an issue that causes slimit to fail
 # https://github.com/dabeaz/ply/issues/63
-ply==3.4
+ply==3.8