diff --git a/config.py b/config.py
index 2b908a4..07dad9f 100644
--- a/config.py
+++ b/config.py
@@ -5,4 +5,5 @@ DEBUG_NO_SHOW = os.environ.get("DEBUG_NO_SHOW", "")
 DEBUG_HEIGHT = int(os.environ.get("DEBUG_HEIGHT", "800"))
 INPUT = os.environ.get("INPUT", "./testdata/input.pdf")
 TEMP_DIR = os.environ.get("TEMP_DIR", "/tmp/dnd-pdf-to-txt.d")
+PARALLEL = int(os.environ.get("PARALLEL", "0"))
 os.makedirs(TEMP_DIR, exist_ok=True)
diff --git a/main.py b/main.py
index 5722594..621173e 100644
--- a/main.py
+++ b/main.py
@@ -13,19 +13,22 @@ def log(*args):
    print(*args, flush=True)
 
 def de_column_ify():
-   q = queue.Queue(maxsize=4)
+   q = queue.Queue(maxsize=4 if config.PARALLEL else 0)
    with pdfplumber.open(config.INPUT) as pdf:
       cropped_pages = []
       with ThreadPool(4) as pool:
          for i in range(len(pdf.pages)):
-            pool.apply_async(de_columnify_page, (q, config.INPUT, pdf.pages[i], ))
+            if config.PARALLEL:
+               pool.apply_async(de_columnify_page, (q, config.INPUT, pdf.pages[i], ))
+            else:
+               de_columnify_page(q, config.INPUT, pdf.pages[i])
          for i in range(len(pdf.pages)):
             log("getting", i, "of", len(pdf.pages))
             got = q.get()
             for got_i in got[1]:
                cropped_pages.append((got[0], got_i.path))
-               #if got_i.chars:
-               #   debug.debug_show(debug.debug_im(got_i.page))
+               if got_i.chars:
+                  debug.debug_show(debug.debug_im(got_i.page))
 
    cropped_pages = sorted(cropped_pages)
    writer = pypdf.PdfWriter()