diff --git a/dom/workers/RuntimeService.cpp b/dom/workers/RuntimeService.cpp
index 143d4f56e51..539305d0660 100644
--- a/dom/workers/RuntimeService.cpp
+++ b/dom/workers/RuntimeService.cpp
@@ -265,14 +265,23 @@ GetWorkerPref(const nsACString& aPref,
   return result;
 }
 
-// This function creates a key for a SharedWorker composed by "name|scriptSpec".
+// This function creates a key for a SharedWorker composed by "shared|name|scriptSpec"
+// and a key for a ServiceWorker composed by "service|scope|scriptSpec".
 // If the name contains a '|', this will be replaced by '||'.
 void
 GenerateSharedWorkerKey(const nsACString& aScriptSpec, const nsACString& aName,
-                        nsCString& aKey)
+                        WorkerType aWorkerType, nsCString& aKey)
 {
   aKey.Truncate();
-  aKey.SetCapacity(aScriptSpec.Length() + aName.Length() + 1);
+  NS_NAMED_LITERAL_CSTRING(sharedPrefix, "shared|");
+  NS_NAMED_LITERAL_CSTRING(servicePrefix, "service|");
+  MOZ_ASSERT(servicePrefix.Length() > sharedPrefix.Length());
+  MOZ_ASSERT(aWorkerType == WorkerTypeShared ||
+             aWorkerType == WorkerTypeService);
+  aKey.SetCapacity(servicePrefix.Length() + aScriptSpec.Length() +
+                   aName.Length() + 1);
+
+  aKey.Append(aWorkerType == WorkerTypeService ? servicePrefix : sharedPrefix);
 
   nsACString::const_iterator start, end;
   aName.BeginReading(start);
@@ -1463,7 +1472,8 @@ RuntimeService::RegisterWorker(JSContext* aCx, WorkerPrivate* aWorkerPrivate)
       const nsCString& sharedWorkerName = aWorkerPrivate->SharedWorkerName();
 
       nsAutoCString key;
-      GenerateSharedWorkerKey(sharedWorkerScriptSpec, sharedWorkerName, key);
+      GenerateSharedWorkerKey(sharedWorkerScriptSpec, sharedWorkerName,
+                              aWorkerPrivate->Type(), key);
       MOZ_ASSERT(!domainInfo->mSharedWorkerInfos.Get(key));
 
       SharedWorkerInfo* sharedWorkerInfo =
@@ -1568,7 +1578,8 @@ RuntimeService::UnregisterWorker(JSContext* aCx, WorkerPrivate* aWorkerPrivate)
       if (match.mSharedWorkerInfo) {
         nsAutoCString key;
         GenerateSharedWorkerKey(match.mSharedWorkerInfo->mScriptSpec,
-                                match.mSharedWorkerInfo->mName, key);
+                                match.mSharedWorkerInfo->mName,
+                                aWorkerPrivate->Type(), key);
         domainInfo->mSharedWorkerInfos.Remove(key);
       }
     }
@@ -2297,7 +2308,7 @@ RuntimeService::CreateSharedWorkerFromLoadInfo(JSContext* aCx,
     NS_ENSURE_SUCCESS(rv, rv);
 
     nsAutoCString key;
-    GenerateSharedWorkerKey(scriptSpec, aName, key);
+    GenerateSharedWorkerKey(scriptSpec, aName, aType, key);
 
     if (mDomainMap.Get(aLoadInfo->mDomain, &domainInfo) &&
         domainInfo->mSharedWorkerInfos.Get(key, &sharedWorkerInfo)) {
@@ -2372,7 +2383,8 @@ RuntimeService::ForgetSharedWorker(WorkerPrivate* aWorkerPrivate)
     if (match.mSharedWorkerInfo) {
       nsAutoCString key;
       GenerateSharedWorkerKey(match.mSharedWorkerInfo->mScriptSpec,
-                              match.mSharedWorkerInfo->mName, key);
+                              match.mSharedWorkerInfo->mName,
+                              aWorkerPrivate->Type(), key);
       domainInfo->mSharedWorkerInfos.Remove(key);
     }
   }
diff --git a/dom/workers/test/serviceworkers/mochitest.ini b/dom/workers/test/serviceworkers/mochitest.ini
index db54f815fa3..6e5b679f82c 100644
--- a/dom/workers/test/serviceworkers/mochitest.ini
+++ b/dom/workers/test/serviceworkers/mochitest.ini
@@ -30,6 +30,7 @@ support-files =
   serviceworker_wrapper.js
   message_receiver.html
   close_test.js
+  serviceworker_not_sharedworker.js
 
 [test_unregister.html]
 [test_installation_simple.html]
@@ -46,3 +47,4 @@ support-files =
 [test_match_all_client_properties.html]
 [test_close.html]
 [test_serviceworker_interfaces.html]
+[test_serviceworker_not_sharedworker.html]
diff --git a/dom/workers/test/serviceworkers/serviceworker_not_sharedworker.js b/dom/workers/test/serviceworkers/serviceworker_not_sharedworker.js
new file mode 100644
index 00000000000..077da2366d3
--- /dev/null
+++ b/dom/workers/test/serviceworkers/serviceworker_not_sharedworker.js
@@ -0,0 +1,21 @@
+function OnMessage(e)
+{
+  if (e.data.msg == "whoareyou") {
+    if ("ServiceWorker" in self) {
+      self.clients.matchAll().then(function(clients) {
+        clients[0].postMessage({result: "serviceworker"});
+      });
+    } else {
+      port.postMessage({result: "sharedworker"});
+    }
+  }
+};
+
+var port;
+onconnect = function(e) {
+  port = e.ports[0];
+  port.onmessage = OnMessage;
+  port.start();
+};
+
+onmessage = OnMessage;
diff --git a/dom/workers/test/serviceworkers/test_serviceworker_not_sharedworker.html b/dom/workers/test/serviceworkers/test_serviceworker_not_sharedworker.html
new file mode 100644
index 00000000000..5fc433bcbeb
--- /dev/null
+++ b/dom/workers/test/serviceworkers/test_serviceworker_not_sharedworker.html
@@ -0,0 +1,72 @@
+<!--
+  Any copyright is dedicated to the Public Domain.
+  http://creativecommons.org/publicdomain/zero/1.0/
+-->
+<!DOCTYPE HTML>
+<html>
+<head>
+  <title>Bug 1141274 - test that service workers and shared workers are separate</title>
+  <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
+</head>
+<body>
+<p id="display"></p>
+<div id="content" style="display: none">
+<iframe></iframe>
+</div>
+<pre id="test"></pre>
+<script class="testbody" type="text/javascript">
+
+  var iframe;
+  const SCOPE = "http://mochi.test:8888/tests/dom/workers/test/serviceworkers/";
+  function runTest() {
+    navigator.serviceWorker.register("serviceworker_not_sharedworker.js",
+                                     {scope: SCOPE})
+      .then(function(registration) {
+        if (registration.installing) {
+          registration.installing.onstatechange = function(e) {
+            e.target.onstatechange = null;
+            setupSW(registration);
+          };
+        } else {
+          setupSW(registration);
+        }
+      });
+  }
+
+  var sw, worker;
+  function setupSW(registration) {
+    sw = registration.waiting || registration.active;
+    worker = new SharedWorker("serviceworker_not_sharedworker.js", SCOPE);
+    worker.port.start();
+    iframe = document.querySelector("iframe");
+    iframe.src = "message_receiver.html";
+    iframe.onload = function() {
+      window.onmessage = function(e) {
+        is(e.data.result, "serviceworker", "We should be talking to a service worker");
+        window.onmessage = null;
+        worker.port.onmessage = function(e) {
+          is(e.data.result, "sharedworker", "We should be talking to a shared worker");
+          registration.unregister().then(function(success) {
+            ok(success, "unregister should succeed");
+            SimpleTest.finish();
+          });
+        };
+        worker.port.postMessage({msg: "whoareyou"});
+      };
+      sw.postMessage({msg: "whoareyou"});
+    };
+  }
+
+  SimpleTest.waitForExplicitFinish();
+  onload = function() {
+    SpecialPowers.pushPrefEnv({"set": [
+      ["dom.serviceWorkers.exemptFromPerDomainMax", true],
+      ["dom.serviceWorkers.enabled", true],
+      ["dom.serviceWorkers.testing.enabled", true]
+    ]}, runTest);
+  };
+</script>
+</pre>
+</body>
+</html>