diff --git a/fuzzers/run_fuzzer.py b/fuzzers/run_fuzzer.py
index 5abeaab8..50b198a6 100755
--- a/fuzzers/run_fuzzer.py
+++ b/fuzzers/run_fuzzer.py
@@ -465,10 +465,9 @@ def run_fuzzer(fuzzer_name, fuzzer_dir, fuzzer_logdir, logger):
 
         # Make sure the file descriptors exist..
         job_rd_fd = os.fdopen(int(job_rd), 'rb', 0)
+        assert job_rd_fd
         job_wr_fd = os.fdopen(int(job_wr), 'rb', 0)
-    else:
-        job_rd_fd = None
-        job_wr_fd = None
+        assert job_wr_fd
 
     p = None
     try:
@@ -481,12 +480,6 @@ def run_fuzzer(fuzzer_name, fuzzer_dir, fuzzer_logdir, logger):
             # control.
             close_fds=False)
 
-        # Close the jobserver files if they were found.
-        if job_rd_fd:
-            job_rd_fd.close()
-        if job_wr_fd:
-            job_wr_fd.close()
-
         while True:
             try:
                 retcode = p.wait(timeout=10)