diff --git a/package-lock.json b/package-lock.json
index 63c81dc..e805147 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1671,7 +1671,8 @@
         "ansi-regex": {
           "version": "2.1.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -1692,12 +1693,14 @@
         "balanced-match": {
           "version": "1.0.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -1712,17 +1715,20 @@
         "code-point-at": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "concat-map": {
           "version": "0.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "console-control-strings": {
           "version": "1.1.0",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -1839,7 +1845,8 @@
         "inherits": {
           "version": "2.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "ini": {
           "version": "1.3.5",
@@ -1851,6 +1858,7 @@
           "version": "1.0.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -1865,6 +1873,7 @@
           "version": "3.0.4",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
@@ -1872,12 +1881,14 @@
         "minimist": {
           "version": "0.0.8",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "minipass": {
           "version": "2.3.5",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -1896,6 +1907,7 @@
           "version": "0.5.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -1976,7 +1988,8 @@
         "number-is-nan": {
           "version": "1.0.1",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -1988,6 +2001,7 @@
           "version": "1.4.0",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -2073,7 +2087,8 @@
         "safe-buffer": {
           "version": "5.1.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -2109,6 +2124,7 @@
           "version": "1.0.2",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -2128,6 +2144,7 @@
           "version": "3.0.1",
           "bundled": true,
           "dev": true,
+          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -2171,12 +2188,14 @@
         "wrappy": {
           "version": "1.0.2",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         },
         "yallist": {
           "version": "3.0.3",
           "bundled": true,
-          "dev": true
+          "dev": true,
+          "optional": true
         }
       }
     },
@@ -4860,6 +4879,11 @@
         "defaults": "^1.0.3"
       }
     },
+    "web-streams-polyfill": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/web-streams-polyfill/-/web-streams-polyfill-2.0.3.tgz",
+      "integrity": "sha512-pOqiHmL3RBAGS+SgOR42RbPU6nc8/n15N2rsOXFYHLnTfs2Z8QHs8AizOeOaYEnhwPN4+hu3M2D9XvAqzvt6MA=="
+    },
     "which": {
       "version": "1.3.1",
       "resolved": "https://registry.npmjs.org/which/-/which-1.3.1.tgz",
diff --git a/package.json b/package.json
index f3f2d7a..9fad49f 100644
--- a/package.json
+++ b/package.json
@@ -31,5 +31,8 @@
     "karma-typescript": "^4.0.0",
     "power-assert": "^1.6.1",
     "typescript": "^3.4.5"
+  },
+  "dependencies": {
+    "web-streams-polyfill": "^2.0.3"
   }
 }
diff --git a/src/streams.ts b/src/streams.ts
index 2d14aa3..0cd825d 100644
--- a/src/streams.ts
+++ b/src/streams.ts
@@ -1,4 +1,5 @@
 /* global ReadableStream TransformStream */
+import 'web-streams-polyfill/dist/polyfill';
 
 export function transformStream(readable: ReadableStream<Uint8Array>, transformer: Transformer<Uint8Array, Uint8Array>, oncancel?: ReadableStreamErrorCallback): ReadableStream<Uint8Array> {
   try {