diff --git a/scalene/scalene_profiler.py b/scalene/scalene_profiler.py
index 230b6c994..c697c8886 100644
--- a/scalene/scalene_profiler.py
+++ b/scalene/scalene_profiler.py
@@ -1393,6 +1393,7 @@ def alloc_sigqueue_processor(x: Optional[List[int]]) -> None:
                     reported_fname,
                     reported_lineno,
                     bytei_str,
+                    thread_id,
                 ) = count_str.split(",")
                 if int(curr_pid) != int(pid):
                     continue
@@ -1406,6 +1407,7 @@ def alloc_sigqueue_processor(x: Optional[List[int]]) -> None:
                         Filename(reported_fname),
                         LineNumber(int(reported_lineno)),
                         ByteCodeIndex(int(bytei_str)),
+                        thread_id
                     )
                 )
 
@@ -1427,6 +1429,7 @@ def alloc_sigqueue_processor(x: Optional[List[int]]) -> None:
                 fname,
                 lineno,
                 bytei,
+                thread_id,
             ) = item
             is_malloc = action == Scalene.MALLOC_ACTION
             count /= Scalene.BYTES_PER_MB
@@ -1491,6 +1494,7 @@ def alloc_sigqueue_processor(x: Optional[List[int]]) -> None:
                 fname,
                 lineno,
                 bytei,
+                thread_id
             ) = item
 
             is_malloc = action == Scalene.MALLOC_ACTION
diff --git a/src/include/sampleheap.hpp b/src/include/sampleheap.hpp
index 3102a04b4..e97d655b5 100644
--- a/src/include/sampleheap.hpp
+++ b/src/include/sampleheap.hpp
@@ -291,18 +291,33 @@ class SampleHeap : public SuperHeap {
     if (_pythonCount == 0) {
       _pythonCount = 1;  // prevent 0/0
     }
+    // Get the thread ID, which must match the logic used by Python.
+    uint64_t thread_id;
+#if defined(__APPLE__) || defined(BSD)
+    // Use the OS X / BSD thread identifier function to get "actual" thread ID.
+    pthread_threadid_np(pthread_self(), &thread_id);
+#elif defined(__linux__)
+    // On Linux, use gettid().
+    thread_id = (uint64_t) gettid();
+#else
+    // On other systems, cast pthread_self and hope for the best.
+    thread_id = (uint64_t) pthread_self();
+#endif
+   
     snprintf_(
         buf, sizeof(buf),
 #if defined(__APPLE__)
-        "%c,%llu,%llu,%f,%d,%p,%s,%d,%d\n\n",
+        "%c,%llu,%llu,%f,%d,%p,%s,%d,%d,%lu\n\n",
 #else
-        "%c,%lu,%lu,%f,%d,%p,%s,%d,%d\n\n",
+        "%c,%lu,%lu,%f,%d,%p,%s,%d,%d,%lu\n\n",
 #endif
         ((sig == MallocSignal) ? 'M' : ((_freedLastMallocTrigger) ? 'f' : 'F')),
         mallocTriggered() + freeTriggered(), count,
         (float)_pythonCount / (_pythonCount + _cCount), getpid(),
         _freedLastMallocTrigger ? _lastMallocTrigger : ptr, filename.c_str(),
-        lineno, bytei);
+        lineno,
+	bytei,
+        thread_id);
     // Ensure we don't report last-malloc-freed multiple times.
     _freedLastMallocTrigger = false;
     getSampleFile().writeToFile(buf);
diff --git a/src/source/pywhere.cpp b/src/source/pywhere.cpp
index 16ab27d59..50fe4a1e7 100644
--- a/src/source/pywhere.cpp
+++ b/src/source/pywhere.cpp
@@ -251,12 +251,16 @@ int whereInPython(std::string& filename, int& lineno, int& bytei) {
   PyPtr<PyFrameObject> frame =
       threadState ? PyThreadState_GetFrame(threadState) : nullptr;
 
+  // EDB: Below commented out to allow correct attribution to individual threads.
+  // As long as the frames contain file and line number information, we are good.
+#if 0
   if (static_cast<PyFrameObject*>(frame) == nullptr) {
     // Various packages may create native threads; attribute what they do
     // to what the main thread is doing, as it's likely to have requested it.
     frame = findMainPythonThread_frame();  // note this may be nullptr
   }
-
+#endif
+  
   auto traceConfig = TraceConfig::getInstance();
   if (!traceConfig) {
     return 0;