diff --git a/tests/run-tests.py b/tests/run-tests.py
--- a/tests/run-tests.py
+++ b/tests/run-tests.py
@@ -1778,10 +1778,11 @@ class TestSuite(unittest.TestSuite):
             except: # re-raises
                 done.put(('!', test, 'run-test raised an error, see traceback'))
                 raise
-            try:
-                channels[channel] = ''
-            except IndexError:
-                pass
+            finally:
+                try:
+                    channels[channel] = ''
+                except IndexError:
+                    pass
 
         def stat():
             count = 0
diff --git a/tests/test-run-tests.t b/tests/test-run-tests.t
--- a/tests/test-run-tests.t
+++ b/tests/test-run-tests.t
@@ -903,6 +903,30 @@ support for bisecting failed tests autom
 
   $ cd ..
 
+Test a broken #if statement doesn't break run-tests threading.
+==============================================================
+  $ mkdir broken
+  $ cd broken
+  $ cat > test-broken.t <<EOF
+  > true
+  > #if notarealhghavefeature
+  >   $ false
+  > #endif
+  > EOF
+  $ for f in 1 2 3 4 ; do
+  > cat > test-works-$f.t <<EOF
+  > This is test case $f
+  >   $ sleep 1
+  > EOF
+  > done
+  $ rt -j 2
+  ....
+  # Ran 5 tests, 0 skipped, 0 warned, 0 failed.
+  skipped: unknown feature: notarealhghavefeature
+  
+  $ cd ..
+  $ rm -rf broken
+
 Test cases in .t files
 ======================
   $ mkdir cases