diff --git a/CONTRIBUTORS b/CONTRIBUTORS
index e9c178840..d522c44c7 100644
--- a/CONTRIBUTORS
+++ b/CONTRIBUTORS
@@ -26,6 +26,7 @@ Aaron Vaage <vaage@google.com>
 Alvaro Velad Galvan <alvaro.velad@mirada.tv>
 Andy Hochhaus <ahochhaus@samegoal.com>
 Benjamin Wallberg <benjamin.wallberg@bonnierbroadcasting.com>
+Boris Cupac <borisrt2309@gmail.com>
 Bryan Huh <bhh1988@gmail.com>
 Chad Assareh <assareh@google.com>
 Chris Fillmore <fillmore.chris@gmail.com>
diff --git a/lib/media/drm_engine.js b/lib/media/drm_engine.js
index 4defd2738..689cdc9b0 100644
--- a/lib/media/drm_engine.js
+++ b/lib/media/drm_engine.js
@@ -1332,10 +1332,11 @@ shaka.media.DrmEngine.prototype.formatFairPlayRequest_ = function(request) {
   // The standard format for FairPlay seems to be to place the request into a
   // POST parameter (spc=).
   const originalPayload = new Uint8Array(request.body);
-  const base64Payload = shaka.util.Uint8ArrayUtils.toBase64(originalPayload);
+  const base64Payload = shaka.util.
+  Uint8ArrayUtils.toStandardBase64(originalPayload);
   const params = 'spc=' + base64Payload;
   request.headers['Content-Type'] = 'application/x-www-form-urlencoded';
-  request.body = shaka.util.StringUtils.toUTF8(params);
+  request.body = shaka.util.StringUtils.toUTF8(encodeURIComponent(params));
 };
 
 
diff --git a/lib/util/uint8array_utils.js b/lib/util/uint8array_utils.js
index 544054483..16e9c2650 100644
--- a/lib/util/uint8array_utils.js
+++ b/lib/util/uint8array_utils.js
@@ -26,6 +26,18 @@ goog.require('shaka.util.StringUtils');
  * @exportDoc
  */
 
+/**
+ * Convert a Uint8Array to a base64 string. The output will be standard alphabet
+ * as opposed to base64url safe alphabet.
+ * @param {!Uint8Array} u8Arr
+ * @return {string}
+ * @export
+ */
+
+shaka.util.Uint8ArrayUtils.toStandardBase64 = function(u8Arr) {
+    const bytes = shaka.util.StringUtils.fromCharCode(u8Arr);
+    return btoa(bytes);
+};
 
 /**
  * Convert a Uint8Array to a base64 string.  The output will always use the
@@ -37,14 +49,12 @@ goog.require('shaka.util.StringUtils');
  * @export
  */
 shaka.util.Uint8ArrayUtils.toBase64 = function(arr, padding) {
-  // btoa expects a "raw string" where each character is interpreted as a byte.
-  const bytes = shaka.util.StringUtils.fromCharCode(arr);
   padding = (padding == undefined) ? true : padding;
-  const base64 = window.btoa(bytes).replace(/\+/g, '-').replace(/\//g, '_');
+  const base64 = shaka.util.Uint8ArrayUtils.toStandardBase64(arr)
+    .replace(/\+/g, '-').replace(/\//g, '_');
   return padding ? base64 : base64.replace(/=*$/, '');
 };
 
-
 /**
  * Convert a base64 string to a Uint8Array.  Accepts either the standard
  * alphabet or the alternate "base64url" alphabet.