diff --git a/CHANGELOG.md b/CHANGELOG.md
index 722cb3f3..65f41439 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -26,6 +26,7 @@
 - fix: remove unreachable backports.functools_lru_cache fallback and dead dependency @williballenthin
 - fix: add missing ELF branch in get_format_from_extension for .elf_ files @williballenthin #3031
 - fix: Scopes.from_dict uses cls instead of self so subclasses return the correct type @williballenthin
+- fix: correct wrong dict key in VMRay _compute_monitor_threads assertion (used thread_id instead of process_id) @williballenthin
 
 ### capa Explorer Web
 
diff --git a/capa/features/extractors/vmray/__init__.py b/capa/features/extractors/vmray/__init__.py
index 0eaf0d4c..07ff35d7 100644
--- a/capa/features/extractors/vmray/__init__.py
+++ b/capa/features/extractors/vmray/__init__.py
@@ -237,7 +237,7 @@ class VMRayAnalysis:
 
             # we expect each monitor thread ID to be unique for its associated monitor process ID e.g. monitor
             # thread ID 10 should not be captured twice for monitor process ID 1
-            assert monitor_thread.thread_id not in self.monitor_threads_by_monitor_process[monitor_thread.thread_id]
+            assert monitor_thread.thread_id not in self.monitor_threads_by_monitor_process[monitor_thread.process_id]
 
             self.monitor_threads_by_monitor_process[monitor_thread.process_id].append(monitor_thread.thread_id)