diff --git a/microsplit/fastq.py b/microsplit/fastq.py
index 9fc154ce0a10099550c2024f82972ab0b2188373..d23c263ba75e647a6da562ddd4e13e0168096f56 100644
--- a/microsplit/fastq.py
+++ b/microsplit/fastq.py
@@ -1,9 +1,9 @@
-def open_output(output_forward, output_reverse, num_processes):
+def open_output(output_forward, output_reverse, write_processes):
     """
     Open output files for writing with pigz compression.
 
     Parameters:
-        num_processes (int): Number of threads for writing.
+        write_processes (int): Number of threads for writing.
         output_forward (str): Path to the forward output file.
         output_reverse (str): Path to the reverse output file.
 
@@ -14,15 +14,15 @@ def open_output(output_forward, output_reverse, num_processes):
     import signal
     import subprocess
     from auxiliary import signal_handler
-    num_processes = int(num_processes/2)
+    write_processes = int(write_processes/2)
     # Open output files for writing
     out_f = subprocess.Popen(
-        args=["pigz", "-c", "-p", str(num_processes)],
+        args=["pigz", "-c", "-p", str(write_processes)],
         stdin=subprocess.PIPE,
         stdout=open(file=output_forward, mode="wt"),
     )
     out_r = subprocess.Popen(
-        ["pigz", "-c", "-p", str(num_processes)],
+        ["pigz", "-c", "-p", str(write_processes)],
         stdin=subprocess.PIPE,
         stdout=open(file=output_reverse, mode="wt"),
     )
@@ -38,7 +38,7 @@ def open_output(output_forward, output_reverse, num_processes):
     )
     return out_f, out_r
 
-def write_fastq_pair(output_queue, output_forward, output_reverse, num_process):
+def write_fastq_pair(output_queue, output_forward, output_reverse, num_process, write_processes):
     """
     Write FastQ file pairs to the output using data from the output queue.
 
@@ -49,7 +49,7 @@ def write_fastq_pair(output_queue, output_forward, output_reverse, num_process):
         num_process (int): Number of fragmenting threads.
     """
     import sys
-    out_f, out_r = open_output(output_forward, output_reverse, num_process)
+    out_f, out_r = open_output(output_forward, output_reverse, write_processes)
     while num_process > 0:
         try:
             data = output_queue.get()