diff --git a/lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp b/lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
index 8f5f1242116f5..084f8012bcc8d 100644
--- a/lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
+++ b/lldb/source/Plugins/Process/elf-core/ProcessElfCore.cpp
@@ -308,7 +308,13 @@ llvm::StringRef ProcessElfCore::GetMainExecutablePath() {
 }
 
 UUID ProcessElfCore::FindModuleUUID(const llvm::StringRef path) {
-  return m_uuids[std::string(path)];
+  // Lookup the UUID for the given path in the map.
+  // Note that this could be called by multiple threads so make sure
+  // we access the map in a thread safe way (i.e. don't use operator[]).
+  auto it = m_uuids.find(std::string(path));
+  if (it != m_uuids.end())
+    return it->second;
+  return UUID();
 }
 
 lldb_private::DynamicLoader *ProcessElfCore::GetDynamicLoader() {
diff --git a/lldb/test/API/functionalities/postmortem/netbsd-core/TestNetBSDCore.py b/lldb/test/API/functionalities/postmortem/netbsd-core/TestNetBSDCore.py
index 179dbdf88fa8a..ff1ef21e02e31 100644
--- a/lldb/test/API/functionalities/postmortem/netbsd-core/TestNetBSDCore.py
+++ b/lldb/test/API/functionalities/postmortem/netbsd-core/TestNetBSDCore.py
@@ -117,8 +117,6 @@ def check_backtrace(self, thread, filename, backtrace):
                 )
 
     def do_test(self, filename, pid, region_count):
-        # Temporary workaround for https://github.com/llvm/llvm-project/issues/159377
-        self.runCmd("settings set target.parallel-module-load false")
         target = self.dbg.CreateTarget(filename)
         process = target.LoadCore(filename + ".core")