diff --git a/src/debugpy/launcher/handlers.py b/src/debugpy/launcher/handlers.py
index e1be768dd..26aaf39c9 100644
--- a/src/debugpy/launcher/handlers.py
+++ b/src/debugpy/launcher/handlers.py
@@ -78,7 +78,7 @@ def property_or_debug_option(prop_name, flag_name):
     process_name = request("processName", compat.filename(sys.executable))
 
     env = os.environ.copy()
-    env_changes = request("env", json.object(unicode))
+    env_changes = request("env", json.object((unicode, type(None))))
     if sys.platform == "win32":
         # Environment variables are case-insensitive on Win32, so we need to normalize
         # both dicts to make sure that env vars specified in the debug configuration
@@ -94,6 +94,7 @@ def property_or_debug_option(prop_name, flag_name):
         # applied to the debuggee, since it will conflict with pydevd.
         env.pop("COV_CORE_SOURCE", None)
     env.update(env_changes)
+    env = {k: v for k, v in env.items() if v is not None}
 
     if request("gevent", False):
         env["GEVENT_SUPPORT"] = "True"
diff --git a/tests/debugpy/test_env.py b/tests/debugpy/test_env.py
index fe572ff8a..09fc7919c 100644
--- a/tests/debugpy/test_env.py
+++ b/tests/debugpy/test_env.py
@@ -12,9 +12,10 @@
 from tests.debug import runners
 
 
+@pytest.mark.parametrize("new_value", [None, "42"])
 @pytest.mark.parametrize("case", ["match_case", "mismatch_case"])
 @pytest.mark.parametrize("run", runners.all_launch)
-def test_env_replace_var(pyfile, target, run, case):
+def test_env_replace_var(pyfile, target, run, case, new_value):
     @pyfile
     def code_to_debug():
         import os
@@ -29,25 +30,36 @@ def code_to_debug():
 
     with debug.Session() as session:
         backchannel = session.open_backchannel()
-        session.config.env[varname if case == "match_case" else varname.lower()] = "42"
+        session.config.env[varname if case == "match_case" else varname.lower()] = new_value
 
         os.environ[varname] = "1"
-        with run(session, target(code_to_debug)):
-            pass
-        del os.environ[varname]
+        try:
+            with run(session, target(code_to_debug)):
+                pass
+        finally:
+            del os.environ[varname]
 
         env = backchannel.receive()
         if case == "match_case":
             # If case matches, debug config should replace global env var regardless
             # of the platform.
-            assert env[varname] == "42"
+            if new_value is None:
+                assert varname not in env
+            else:
+                assert env[varname] == "42"
         elif sys.platform == "win32":
             # On Win32, variable names are case-insensitive, so debug config should
             # replace the global env var even if there is a case mismatch.
-            assert env[varname] == "42"
+            if new_value is None:
+                assert varname not in env
+            else:
+                assert env[varname] == "42"
             assert varname.lower() not in env
         else:
             # On other platforms, variable names are case-sensitive, so case mismatch
             # should result in two different variables.
             assert env[varname] == "1"
-            assert env[varname.lower()] == "42"
+            if new_value is None:
+                assert varname.lower() not in env
+            else:
+                assert env[varname.lower()] == "42"