diff --git a/caps/BasePrincipal.cpp b/caps/BasePrincipal.cpp
index ed053ab8bc..cc77bcb9b5 100644
--- a/caps/BasePrincipal.cpp
+++ b/caps/BasePrincipal.cpp
@@ -51,7 +51,7 @@ OriginAttributes::CreateSuffix(nsACString& aStr) const
 
   params->Serialize(value);
   if (!value.IsEmpty()) {
-    aStr.AppendLiteral("!");
+    aStr.AppendLiteral("^");
     aStr.Append(NS_ConvertUTF16toUTF8(value));
   }
 }
@@ -117,7 +117,7 @@ OriginAttributes::PopulateFromSuffix(const nsACString& aStr)
     return true;
   }
 
-  if (aStr[0] != '!') {
+  if (aStr[0] != '^') {
     return false;
   }
 
@@ -134,7 +134,7 @@ OriginAttributes::PopulateFromOrigin(const nsACString& aOrigin,
 {
   // RFindChar is only available on nsCString.
   nsCString origin(aOrigin);
-  int32_t pos = origin.RFindChar('!');
+  int32_t pos = origin.RFindChar('^');
 
   if (pos == kNotFound) {
     aOriginNoSuffix = origin;
diff --git a/dom/apps/tests/unit/test_moziapplication.js b/dom/apps/tests/unit/test_moziapplication.js
index 5488df18e2..8a6daa1452 100644
--- a/dom/apps/tests/unit/test_moziapplication.js
+++ b/dom/apps/tests/unit/test_moziapplication.js
@@ -51,7 +51,7 @@ add_test(() => {
   });
 
   Assert.ok(mozapp.principal, "app principal should exist");
-  let expectedPrincipalOrigin = app.origin + "!appId=" + app.localId;
+  let expectedPrincipalOrigin = app.origin + "^appId=" + app.localId;
   Assert.equal(mozapp.principal.origin, expectedPrincipalOrigin,
                "app principal origin ok");
   Assert.equal(mozapp.principal.appId, app.localId, "app principal appId ok");
diff --git a/toolkit/modules/BrowserUtils.jsm b/toolkit/modules/BrowserUtils.jsm
index eb20647a2b..d23200151b 100644
--- a/toolkit/modules/BrowserUtils.jsm
+++ b/toolkit/modules/BrowserUtils.jsm
@@ -115,7 +115,7 @@ this.BrowserUtils = {
       throw new Error("principalFromOrigin does not support nsNullPrincipal");
     }
 
-    var parts = aOriginString.split('!');
+    var parts = aOriginString.split('^');
     if (parts.length > 2) {
       throw new Error("bad origin string: " + aOriginString);
     }