diff --git a/blowfish.h b/blowfish.h
index 591f3ab6fe29158aed3f0dbbd642934a2d56f1a4..efa287f5e928fa570d41a035fc7887d6be2885ab 100644
--- a/blowfish.h
+++ b/blowfish.h
@@ -47,7 +47,7 @@ struct blowfish_ctx
   uint32_t s1[256];
   uint32_t s2[256];
   uint32_t s3[256];
-  uint32_t p[_BLOWFISH_ROUNDS];
+  uint32_t p[_BLOWFISH_ROUNDS+2];
   enum blowfish_error status;
 };