diff --git a/lib/zlib.js b/lib/zlib.js
index 7742e68ad6e..b6817749bae 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -277,6 +277,12 @@ function isValidFlushFlag(flag) {
          flag === constants.Z_BLOCK;
 }
 
+const strategies = [constants.Z_FILTERED,
+                    constants.Z_HUFFMAN_ONLY,
+                    constants.Z_RLE,
+                    constants.Z_FIXED,
+                    constants.Z_DEFAULT_STRATEGY];
+
 // the Zlib class they all inherit from
 // This thing manages the queue of requests, and returns
 // true or false if there is anything in the queue when
@@ -326,15 +332,8 @@ function Zlib(opts, mode) {
     }
   }
 
-  if (opts.strategy) {
-    if (opts.strategy != constants.Z_FILTERED &&
-        opts.strategy != constants.Z_HUFFMAN_ONLY &&
-        opts.strategy != constants.Z_RLE &&
-        opts.strategy != constants.Z_FIXED &&
-        opts.strategy != constants.Z_DEFAULT_STRATEGY) {
-      throw new Error('Invalid strategy: ' + opts.strategy);
-    }
-  }
+  if (opts.strategy && !(strategies.includes(opts.strategy)))
+    throw new Error('Invalid strategy: ' + opts.strategy);
 
   if (opts.dictionary) {
     if (!(opts.dictionary instanceof Buffer)) {
@@ -378,7 +377,7 @@ function Zlib(opts, mode) {
   this.once('end', this.close);
 
   Object.defineProperty(this, '_closed', {
-    get: () => { return !this._handle; },
+    get: () => !this._handle,
     configurable: true,
     enumerable: true
   });
@@ -391,13 +390,8 @@ Zlib.prototype.params = function(level, strategy, callback) {
       level > constants.Z_MAX_LEVEL) {
     throw new RangeError('Invalid compression level: ' + level);
   }
-  if (strategy != constants.Z_FILTERED &&
-      strategy != constants.Z_HUFFMAN_ONLY &&
-      strategy != constants.Z_RLE &&
-      strategy != constants.Z_FIXED &&
-      strategy != constants.Z_DEFAULT_STRATEGY) {
+  if (!(strategies.includes(strategy)))
     throw new TypeError('Invalid strategy: ' + strategy);
-  }
 
   if (this._level !== level || this._strategy !== strategy) {
     var self = this;
diff --git a/test/parallel/test-zlib-deflate-constructors.js b/test/parallel/test-zlib-deflate-constructors.js
index 2f23dc595ec..3aef067162f 100644
--- a/test/parallel/test-zlib-deflate-constructors.js
+++ b/test/parallel/test-zlib-deflate-constructors.js
@@ -86,6 +86,12 @@ assert.doesNotThrow(
   () => { new zlib.Deflate({ strategy: zlib.constants.Z_DEFAULT_STRATEGY}); }
 );
 
+// Throws if opt.strategy is the wrong type.
+assert.throws(
+  () => { new zlib.Deflate({strategy: '' + zlib.constants.Z_RLE }); },
+  /^Error: Invalid strategy: 3$/
+);
+
 // Throws if opts.strategy is invalid
 assert.throws(
   () => { new zlib.Deflate({strategy: 'this is a bogus strategy'}); },