diff --git a/security/sandbox/linux/broker/SandboxBroker.cpp b/security/sandbox/linux/broker/SandboxBroker.cpp
index 5a44669f9e1d..5cd7d8650fe5 100644
--- a/security/sandbox/linux/broker/SandboxBroker.cpp
+++ b/security/sandbox/linux/broker/SandboxBroker.cpp
@@ -147,23 +147,19 @@ void SandboxBroker::Policy::AddPath(int aPerms, const char* aPath,
                                     AddCondition aCond) {
   nsDependentCString path(aPath);
   MOZ_ASSERT(path.Length() <= kMaxPathLen);
-  int perms;
   if (aCond == AddIfExistsNow) {
     struct stat statBuf;
     if (lstat(aPath, &statBuf) != 0) {
       return;
     }
   }
-  if (!mMap.Get(path, &perms)) {
-    perms = MAY_ACCESS;
-  } else {
-    MOZ_ASSERT(perms & MAY_ACCESS);
-  }
+  auto& perms = mMap.LookupOrInsert(path, MAY_ACCESS);
+  MOZ_ASSERT(perms & MAY_ACCESS);
+
   if (SandboxInfo::Get().Test(SandboxInfo::kVerbose)) {
     SANDBOX_LOG_ERROR("policy for %s: %d -> %d", aPath, perms, perms | aPerms);
   }
   perms |= aPerms;
-  mMap.InsertOrUpdate(path, perms);
 }
 
 void SandboxBroker::Policy::AddTree(int aPerms, const char* aPath) {
@@ -229,18 +225,15 @@ void SandboxBroker::Policy::AddPrefix(int aPerms, const char* aPath) {
 
 void SandboxBroker::Policy::AddPrefixInternal(int aPerms,
                                               const nsACString& aPath) {
-  int origPerms;
-  if (!mMap.Get(aPath, &origPerms)) {
-    origPerms = MAY_ACCESS;
-  } else {
-    MOZ_ASSERT(origPerms & MAY_ACCESS);
-  }
-  int newPerms = origPerms | aPerms | RECURSIVE;
+  auto& perms = mMap.LookupOrInsert(aPath, MAY_ACCESS);
+  MOZ_ASSERT(perms & MAY_ACCESS);
+
+  int newPerms = perms | aPerms | RECURSIVE;
   if (SandboxInfo::Get().Test(SandboxInfo::kVerbose)) {
     SANDBOX_LOG_ERROR("policy for %s: %d -> %d",
-                      PromiseFlatCString(aPath).get(), origPerms, newPerms);
+                      PromiseFlatCString(aPath).get(), perms, newPerms);
   }
-  mMap.InsertOrUpdate(aPath, newPerms);
+  perms = newPerms;
 }
 
 void SandboxBroker::Policy::AddFilePrefix(int aPerms, const char* aDir,