diff --git a/lib/util/config_utils.js b/lib/util/config_utils.js
index 9fda7d6e20..0a31777a5e 100644
--- a/lib/util/config_utils.js
+++ b/lib/util/config_utils.js
@@ -51,7 +51,9 @@ shaka.util.ConfigUtils.mergeConfigObjects =
      */
     var copyObject = !!({
       '.abr.manager': true
-    })[subPath];
+    })[subPath] || !!({
+      'serverCertificate': true
+    })[k];
 
     // The order of these checks is important.
     if (!ignoreKeys && !(k in destination)) {
diff --git a/test/player_unit.js b/test/player_unit.js
index 2bcee85df6..43b85051ec 100644
--- a/test/player_unit.js
+++ b/test/player_unit.js
@@ -610,6 +610,29 @@ describe('Player', function() {
       expect(newConfig.manifest.dash.customScheme).not.toBe(badCustomScheme2);
       expect(logWarnSpy).not.toHaveBeenCalled();
     });
+
+    // Regression test for https://github.com/google/shaka-player/issues/784
+    it('does not throw when overwriting serverCertificate', function() {
+      player.configure({
+        drm: {
+          advanced: {
+            'com.widevine.alpha': {
+              serverCertificate: new Uint8Array(1)
+            }
+          }
+        }
+      });
+
+      player.configure({
+        drm: {
+          advanced: {
+            'com.widevine.alpha': {
+              serverCertificate: new Uint8Array(2)
+            }
+          }
+        }
+      });
+    });
   });
 
   describe('AbrManager', function() {