diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,6 @@
+2025-09-07
+        * Version bump (4.5.1). (#666)
+
 2025-07-07
         * Version bump (4.5). (#642)
 
diff --git a/copilot-c99.cabal b/copilot-c99.cabal
--- a/copilot-c99.cabal
+++ b/copilot-c99.cabal
@@ -1,6 +1,6 @@
 cabal-version             : >= 1.10
 name                      : copilot-c99
-version                   : 4.5
+version                   : 4.5.1
 synopsis                  : A compiler for Copilot targeting C99.
 description               :
   This package is a back-end from Copilot to C.
@@ -45,7 +45,7 @@
                           , mtl                 >= 2.2 && < 2.4
                           , pretty              >= 1.1 && < 1.2
 
-                          , copilot-core        >= 4.5   && < 4.6
+                          , copilot-core        >= 4.5.1 && < 4.6
                           , language-c99        >= 0.2.0 && < 0.3
                           , language-c99-simple >= 0.3   && < 0.4