diff --git a/CHANGELOG.md b/CHANGELOG.md
index e929113..d578939 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -2,6 +2,7 @@
 
 ## [unreleased]
 * Add `u.is` to test predicates in a single path. (https://github.com/substantial/updeep/issues/13)
+* Rename `u.in` to `u.updateIn`. With `u.is` and `u.if` it was too confusing.
 
 ## [0.4.0]
 * Add `u.if` and `u.ifElse` to conditionally update objects. (https://github.com/substantial/updeep/issues/12)
diff --git a/README.md b/README.md
index a74553d..564581e 100644
--- a/README.md
+++ b/README.md
@@ -117,24 +117,24 @@ u({ x: { [key]: 3 } }, { x: { a: 0, b: 0 } });
 // => { x: { a: 0, b: 3 } }
 ```
 
-### `u.in(path(, value)(, object))`
+### `u.updateIn(path(, value)(, object))`
 
 Update a single value with a simple string or array path.
 
 ```js
-u.in('a.b', 3, { a: { b: 0 } });
+u.updateIn('a.b', 3, { a: { b: 0 } });
 // => { a: { b: 3 } };
 ```
 
 ```js
 function inc(i) { return i + 1; }
-u.in('a.b', inc, { a: { b: 0 } });
+u.updateIn('a.b', inc, { a: { b: 0 } });
 // => { a: { b: 1 } };
 ```
 
 ```js
 u({
-  x: u.in(['a', 'b'], 3)
+  x: u.updateIn(['a', 'b'], 3)
 }, { x: { a: { b: 0 } } });
 // => { x: { a: { b: 3 } } };
 ```
@@ -253,7 +253,7 @@ u.is('a.b', isEven, { a: { b: 4 } });
 
 ```js
 u({
-  person: u.if(u.is('name.first', 'Jen'), u.in('name.last', 'Simpson'))
+  person: u.if(u.is('name.first', 'Jen'), u.updateIn('name.last', 'Simpson'))
 }, { person: { name: { first: 'Jen', last: 'Matthews' } } });
 // => { person: { name: { first: 'Jen', last: 'Simpson' } } }
 ```
diff --git a/lib/index.js b/lib/index.js
index 486343a..97267d7 100644
--- a/lib/index.js
+++ b/lib/index.js
@@ -1,5 +1,5 @@
 import freeze from './freeze';
-import _in from './in';
+import updateIn from './updateIn';
 import is from './is';
 import ifElse from './ifElse';
 import map from './map';
@@ -14,7 +14,7 @@ const u = update;
 
 u.if = ifElse(_, _, {});
 u.ifElse = ifElse;
-u.in = _in;
+u.updateIn = updateIn;
 u.is = is;
 u.freeze = freeze;
 u.map = map;
diff --git a/lib/in.js b/lib/updateIn.js
similarity index 100%
rename from lib/in.js
rename to lib/updateIn.js
diff --git a/test/in-spec.js b/test/updateIn-spec.js
similarity index 71%
rename from test/in-spec.js
rename to test/updateIn-spec.js
index 0e3c0d3..6c15fb3 100644
--- a/test/in-spec.js
+++ b/test/updateIn-spec.js
@@ -1,45 +1,45 @@
 import { expect } from 'chai';
 import u from '../lib';
 
-describe('u.in', () => {
+describe('u.updateIn', () => {
   it('can update a single path described with a string', () => {
     const object = { a: { b: 0 } };
-    const result = u.in('a.b', 3, object);
+    const result = u.updateIn('a.b', 3, object);
     expect(result).to.eql({ a: { b: 3 } });
   });
 
   it('can update a single path described with a string with a function', () => {
     const inc = x => x + 1;
     const object = { a: { b: 0 } };
-    const result = u.in('a.b', inc, object);
+    const result = u.updateIn('a.b', inc, object);
     expect(result).to.eql({ a: { b: 1 } });
   });
 
   it('can update a single path described with an array', () => {
     const object = { a: { b: 0 } };
-    const result = u.in(['a', 'b'], 3, object);
+    const result = u.updateIn(['a', 'b'], 3, object);
     expect(result).to.eql({ a: { b: 3 } });
   });
 
   it('can update arrays', () => {
     const object = { a: [0, 0, 0] };
-    const result = u.in('a.1', 3, object);
+    const result = u.updateIn('a.1', 3, object);
     expect(result).to.eql({ a: [0, 3, 0] });
   });
 
   it('can be partially applied', () => {
     const object = { a: { b: 0 } };
-    const result = u.in('a.b')(3)(object);
+    const result = u.updateIn('a.b')(3)(object);
     expect(result).to.eql({ a: { b: 3 } });
   });
 
   it('replaces the object outright if the path is empty', () => {
     const object = {};
-    const result = u.in('', 3, object);
+    const result = u.updateIn('', 3, object);
     expect(result).to.equal(3);
   });
 
   it('freezes the result', () => {
-    expect(Object.isFrozen(u.in('a', 0, {}))).to.be.true;
+    expect(Object.isFrozen(u.updateIn('a', 0, {}))).to.be.true;
   });
 });