diff --git a/CHANGELOG b/CHANGELOG
--- a/CHANGELOG
+++ b/CHANGELOG
@@ -1,3 +1,7 @@
+2026-01-07
+        * Version bump (4.6.1). (#705)
+        * Relax version constraint on optparse-applicative. (#603)
+
 2025-11-07
         * Version bump (4.6). (#679)
 
diff --git a/copilot.cabal b/copilot.cabal
--- a/copilot.cabal
+++ b/copilot.cabal
@@ -1,5 +1,5 @@
 name:                copilot
-version:             4.6
+version:             4.6.1
 cabal-version:       >= 1.10
 license:             BSD3
 license-file:        LICENSE
@@ -48,16 +48,16 @@
       -fno-warn-orphans
     build-depends:
                        base                  >= 4.9  && < 5
-                     , optparse-applicative  >= 0.14 && < 0.19
+                     , optparse-applicative  >= 0.14 && < 0.20
                      , directory             >= 1.3  && < 1.4
                      , filepath              >= 1.4  && < 1.6
 
-                     , copilot-core          >= 4.6 && < 4.7
-                     , copilot-theorem       >= 4.6 && < 4.7
-                     , copilot-language      >= 4.6 && < 4.7
-                     , copilot-libraries     >= 4.6 && < 4.7
-                     , copilot-c99           >= 4.6 && < 4.7
-                     , copilot-prettyprinter >= 4.6 && < 4.7
+                     , copilot-core          >= 4.6.1 && < 4.7
+                     , copilot-theorem       >= 4.6.1 && < 4.7
+                     , copilot-language      >= 4.6.1 && < 4.7
+                     , copilot-libraries     >= 4.6.1 && < 4.7
+                     , copilot-c99           >= 4.6.1 && < 4.7
+                     , copilot-prettyprinter >= 4.6.1 && < 4.7
 
 
     exposed-modules: Language.Copilot, Language.Copilot.Main