diff --git a/doc/api/deprecations.md b/doc/api/deprecations.md
index 01ed6fa7c5b..b5b82cace3a 100644
--- a/doc/api/deprecations.md
+++ b/doc/api/deprecations.md
@@ -988,6 +988,9 @@ instead.
 
 <!-- YAML
 changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/50488
+    description: Runtime deprecation.
   - version:
     - v6.12.0
     - v4.8.6
@@ -1000,7 +1003,7 @@ changes:
     description: Documentation-only deprecation.
 -->
 
-Type: Documentation-only
+Type: Runtime
 
 The [`util.isBoolean()`][] API is deprecated.
 
diff --git a/lib/util.js b/lib/util.js
index 2bb310830fb..91485e30530 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -391,8 +391,10 @@ module.exports = {
   isArray: deprecate(ArrayIsArray,
                      'The `util.isArray` API is deprecated. Please use `Array.isArray()` instead.',
                      'DEP0044'),
-  isBoolean,
-  isBuffer,
+  isBoolean: deprecate(isBoolean,
+                       'The `util.isBoolean` API is deprecated.  Please use `typeof arg === "boolean"` instead.',
+                       'DEP0045'),
+  isBuffer: deprecate(isBuffer, 'The `util.isBuffer API is deprecated.', 'DEP0046'),
   isDeepStrictEqual(a, b) {
     if (internalDeepEqual === undefined) {
       internalDeepEqual = require('internal/util/comparisons')