diff --git a/core/bison/checksums b/core/bison/checksums
index a3ccacf4..ab17f9b4 100644
--- a/core/bison/checksums
+++ b/core/bison/checksums
@@ -1 +1 @@
-4c17e99881978fa32c05933c5262457fa5b2b611668454f8dc2a695cd6b3720c  bison-3.5.4.tar.xz
+9145f59d184c5703a3857c074c1a570c9606be0e9471dd6548c9192e80ce30da  bison-3.5.91.tar.xz
diff --git a/core/bison/sources b/core/bison/sources
index 46836926..e4c66567 100644
--- a/core/bison/sources
+++ b/core/bison/sources
@@ -1 +1 @@
-https://ftp.gnu.org/gnu/bison/bison-3.5.4.tar.xz
+https://ftp.gnu.org/gnu/bison/bison-3.5.91.tar.xz
diff --git a/core/bison/version b/core/bison/version
index 7fc0a169..82cd7b41 100644
--- a/core/bison/version
+++ b/core/bison/version
@@ -1 +1 @@
-3.5.4 1
+3.5.91 1