diff --git a/TODO.md b/TODO.md
index 60f8f6a..7df6b3d 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,5 +1,3 @@
-[refactoring] extract `merge-nothing`
-
 [refactoring] extract `implies`
 
 [refactoring] should not define handlers of `merge` in one file
diff --git a/src/merge/index.ts b/src/merge/index.ts
index ad41461..4d2f039 100644
--- a/src/merge/index.ts
+++ b/src/merge/index.ts
@@ -2,7 +2,7 @@ export * from "./detectMergeConflict.js"
 export * from "./merge-belief-system.js"
 export * from "./merge-belief.js"
 export * from "./merge-interval.js"
+export * from "./merge-nothing.js"
 export * from "./merge-number.js"
 export * from "./merge.js"
-// export * from "./merge-nothing.js"
 export * from "./MergeConflict.js"
diff --git a/src/merge/merge-nothing.ts b/src/merge/merge-nothing.ts
new file mode 100644
index 0000000..eb6be53
--- /dev/null
+++ b/src/merge/merge-nothing.ts
@@ -0,0 +1,10 @@
+import { isNothing } from "../cell/index.js"
+import { defineHandler } from "../generic/index.js"
+import { merge } from "./merge.js"
+
+function isAnything(x: any): true {
+  return true
+}
+
+defineHandler(merge, [isAnything, isNothing], (content, increment) => content)
+defineHandler(merge, [isNothing, isAnything], (content, increment) => increment)
diff --git a/src/merge/merge.ts b/src/merge/merge.ts
index edba9d5..107a9a9 100644
--- a/src/merge/merge.ts
+++ b/src/merge/merge.ts
@@ -1,5 +1,4 @@
-import { isNothing } from "../cell/index.js"
-import { defineGeneric, defineHandler } from "../generic/index.js"
+import { defineGeneric } from "../generic/index.js"
 import { log } from "../utils/log.js"
 
 // # The contract of `merge`
@@ -70,10 +69,3 @@ export const merge = defineGeneric({
 export function implies<A, B>(x: A, y: B): boolean {
   return merge(x, y) === x
 }
-
-function isAnything(x: any): true {
-  return true
-}
-
-defineHandler(merge, [isAnything, isNothing], (content, increment) => content)
-defineHandler(merge, [isNothing, isAnything], (content, increment) => increment)