1 files changed, 24 insertions, 10 deletions

diff --git a/lib/zlib.js b/lib/zlib.js
index 00be56dffc..c1cc0a2c54 100644
--- a/lib/zlib.js
+++ b/lib/zlib.js
@@ -182,37 +182,37 @@ class Zlib extends Transform {
     this._finishFlushFlag = opts.finishFlush !== undefined ?
       opts.finishFlush : constants.Z_FINISH;
 
-    if (opts.chunkSize) {
+    if (opts.chunkSize !== undefined) {
       if (opts.chunkSize < constants.Z_MIN_CHUNK) {
         throw new RangeError('Invalid chunk size: ' + opts.chunkSize);
       }
     }
 
-    if (opts.windowBits) {
+    if (opts.windowBits !== undefined) {
       if (opts.windowBits < constants.Z_MIN_WINDOWBITS ||
           opts.windowBits > constants.Z_MAX_WINDOWBITS) {
         throw new RangeError('Invalid windowBits: ' + opts.windowBits);
       }
     }
 
-    if (opts.level) {
+    if (opts.level !== undefined) {
       if (opts.level < constants.Z_MIN_LEVEL ||
           opts.level > constants.Z_MAX_LEVEL) {
         throw new RangeError('Invalid compression level: ' + opts.level);
       }
     }
 
-    if (opts.memLevel) {
+    if (opts.memLevel !== undefined) {
       if (opts.memLevel < constants.Z_MIN_MEMLEVEL ||
           opts.memLevel > constants.Z_MAX_MEMLEVEL) {
         throw new RangeError('Invalid memLevel: ' + opts.memLevel);
       }
     }
 
-    if (opts.strategy && isInvalidStrategy(opts.strategy))
+    if (opts.strategy !== undefined && isInvalidStrategy(opts.strategy))
       throw new TypeError('Invalid strategy: ' + opts.strategy);
 
-    if (opts.dictionary) {
+    if (opts.dictionary !== undefined) {
       if (!ArrayBuffer.isView(opts.dictionary)) {
         throw new TypeError(
           'Invalid dictionary: it should be a Buffer, TypedArray, or DataView');
@@ -224,14 +224,28 @@ class Zlib extends Transform {
     this._hadError = false;
 
     var level = constants.Z_DEFAULT_COMPRESSION;
-    if (typeof opts.level === 'number') level = opts.level;
+    if (Number.isFinite(opts.level)) {
+      level = opts.level;
+    }
 
     var strategy = constants.Z_DEFAULT_STRATEGY;
-    if (typeof opts.strategy === 'number') strategy = opts.strategy;
+    if (Number.isFinite(opts.strategy)) {
+      strategy = opts.strategy;
+    }
+
+    var windowBits = constants.Z_DEFAULT_WINDOWBITS;
+    if (Number.isFinite(opts.windowBits)) {
+      windowBits = opts.windowBits;
+    }
+
+    var memLevel = constants.Z_DEFAULT_MEMLEVEL;
+    if (Number.isFinite(opts.memLevel)) {
+      memLevel = opts.memLevel;
+    }
 
-    this._handle.init(opts.windowBits || constants.Z_DEFAULT_WINDOWBITS,
+    this._handle.init(windowBits,
                       level,
-                      opts.memLevel || constants.Z_DEFAULT_MEMLEVEL,
+                      memLevel,
                       strategy,
                       opts.dictionary);