diff --git a/benchmark/zlib/deflate.js b/benchmark/zlib/deflate.js
index 5e86d659803747..6d3bda90c6fdfa 100644
--- a/benchmark/zlib/deflate.js
+++ b/benchmark/zlib/deflate.js
@@ -9,6 +9,8 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, method, inputLen }) {
+  // Default method value for testing.
+  method = method || 'deflate';
   const chunk = Buffer.alloc(inputLen, 'a');
 
   var i = 0;
diff --git a/benchmark/zlib/inflate.js b/benchmark/zlib/inflate.js
index 11bc2cce700b40..09379c00c1250b 100644
--- a/benchmark/zlib/inflate.js
+++ b/benchmark/zlib/inflate.js
@@ -9,6 +9,8 @@ const bench = common.createBenchmark(main, {
 });
 
 function main({ n, method, inputLen }) {
+  // Default method value for tests.
+  method = method || 'inflate';
   const chunk = zlib.deflateSync(Buffer.alloc(inputLen, 'a'));
 
   let i = 0;
diff --git a/test/benchmark/test-benchmark-zlib.js b/test/benchmark/test-benchmark-zlib.js
index 4b7e340b8f7abf..adc7e3d47b040d 100644
--- a/test/benchmark/test-benchmark-zlib.js
+++ b/test/benchmark/test-benchmark-zlib.js
@@ -10,7 +10,7 @@ runBenchmark('zlib',
                'chunkLen=1024',
                'duration=0.001',
                'inputLen=1024',
-               'method=deflate',
+               'method=',
                'n=1',
                'options=true',
                'type=Deflate',