diff --git a/lib/core/common.py b/lib/core/common.py
index c053a9f06..a18fbd0ff 100644
--- a/lib/core/common.py
+++ b/lib/core/common.py
@@ -4007,7 +4007,7 @@ def removeReflectiveValues(content, payload, suppressWarning=False):
                     thread.start()
                     thread.join(REFLECTED_REPLACEMENT_TIMEOUT)
 
-                    if thread.isAlive():
+                    if thread.is_alive():
                         kb.reflectiveMechanism = False
                         retVal = content
                         if not suppressWarning:
diff --git a/lib/core/threads.py b/lib/core/threads.py
index c717681fe..e782cf76b 100644
--- a/lib/core/threads.py
+++ b/lib/core/threads.py
@@ -175,7 +175,7 @@ def runThreads(numThreads, threadFunction, cleanupFunction=None, forwardExceptio
         while alive:
             alive = False
             for thread in threads:
-                if thread.isAlive():
+                if thread.is_alive():
                     alive = True
                     time.sleep(0.1)
 
diff --git a/lib/utils/timeout.py b/lib/utils/timeout.py
index 27c716705..6f0e2b198 100644
--- a/lib/utils/timeout.py
+++ b/lib/utils/timeout.py
@@ -31,7 +31,7 @@ def timeout(func, args=None, kwargs=None, duration=1, default=None):
     thread.start()
     thread.join(duration)
 
-    if thread.isAlive():
+    if thread.is_alive():
         return default, TIMEOUT_STATE.TIMEOUT
     else:
         return thread.result, thread.timeout_state