diff --git a/zpooliostat.py b/zpooliostat.py
index 8d93143..619ccf9 100644
--- a/zpooliostat.py
+++ b/zpooliostat.py
@@ -36,14 +36,6 @@ def runZpoolIostat():
 
     # Check the return code (0 for success)
     if result.returncode == 0:
-        # Check if the file exists
-        if not os.path.exists(filename):
-            # Create the file in write mode ('w') if it doesn't exist
-            with open(filename, "w", newline="") as csvfile:
-                csv_writer = csv.writer(csvfile)
-                # Write the header row (optional)
-                csv_writer.writerow(headerRow)
-
         # Access the captured output as a string
         output = result.stdout
 
@@ -81,6 +73,14 @@ def runZpoolIostat():
                         poolname = lineData[0]
                         filename = poolname + "-zio.csv"
 
+                    # Check if the file exists
+                    if not os.path.exists(filename):
+                        # Create the file in write mode ('w') if it doesn't exist
+                        with open(filename, "w", newline="") as csvfile:
+                            csv_writer = csv.writer(csvfile)
+                            # Write the header row (optional)
+                            csv_writer.writerow(headerRow)
+
                     # Now open the file in append mode ('a')
                     with open(filename, "a", newline="") as csvfile:
                         csv_writer = csv.writer(csvfile)