diff --git a/stocproc/config.py b/stocproc/config.py
new file mode 100644
index 0000000..fd92acd
--- /dev/null
+++ b/stocproc/config.py
@@ -0,0 +1,7 @@
+import configparser
+
+config = configparser.ConfigParser()
+config.read("stocproc.ini")
+
+
+USE_NORMALIZED_DIFF = config["FFT"].getboolean("use_normalized_diff", fallback=False)
diff --git a/stocproc/method_ft.py b/stocproc/method_ft.py
index 6a11587..5148356 100644
--- a/stocproc/method_ft.py
+++ b/stocproc/method_ft.py
@@ -24,6 +24,7 @@ import warnings
 MAX_FLOAT = sys.float_info.max
 log = logging.getLogger(__name__)
 
+from .config import USE_NORMALIZED_DIFF
 
 class FTReferenceError(Exception):
     pass
@@ -330,7 +331,11 @@ def _relDiff(xRef, x, norm=1):
 
 
 def _absDiff(xRef, x, norm=1):
-    return np.max(np.abs(xRef - x)) / norm
+    diff = np.max(np.abs(xRef - x))
+    if USE_NORMALIZED_DIFF:
+        return diff / norm
+    else:
+        return diff
 
 
 def _f_opt_for_SLSQP_minimizer(