diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,4 +1,7 @@
 2024-01-07
+        * Version bump (3.18.1). (#493)
+
+2024-01-07
         * Version bump (3.18). (#487)
         * Change return type of main generated for tests. (#468)
         * Print constants in tests using portable suffixes. (#471).
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                   : 3.18
+version                   : 3.18.1
 synopsis                  : A compiler for Copilot targeting C99.
 description               :
   This package is a back-end from Copilot to C.
@@ -45,9 +45,9 @@
                           , mtl                 >= 2.2 && < 2.4
                           , pretty              >= 1.1 && < 1.2
 
-                          , copilot-core        >= 3.18  && < 3.19
-                          , language-c99        >= 0.2.0 && < 0.3
-                          , language-c99-simple >= 0.3   && < 0.4
+                          , copilot-core        >= 3.18.1 && < 3.19
+                          , language-c99        >= 0.2.0  && < 0.3
+                          , language-c99-simple >= 0.3    && < 0.4
 
   exposed-modules         : Copilot.Compile.C99