diff --git a/common/helpers.py b/common/helpers.py
index d262b64..b494d4d 100644
--- a/common/helpers.py
+++ b/common/helpers.py
@@ -65,7 +65,7 @@ def pos_ext_from_data_ext(ext):
     if WFPC2.DATA_FILE_EXT.__contains__(ext):
         return WFPC2.POS_FILE_EXT
 
-    logging.error("Couldn't find a match for %s" % ext)
+    raise ValueError("Couldn't find a match for extension: '{}'".format(ext))
 
 
 class TimeoutError(Exception):
diff --git a/common/instruments.py b/common/instruments.py
index e040df6..0001f1f 100644
--- a/common/instruments.py
+++ b/common/instruments.py
@@ -86,3 +86,5 @@ def instrument_from_name(name):
 
         if WFPC2.NAME == name:
             return WFPC2
+
+        raise ValueError("Unknown instrument name: '{}'".format(name))
diff --git a/lib/crstats.py b/lib/crstats.py
index ac30224..3f3989b 100644
--- a/lib/crstats.py
+++ b/lib/crstats.py
@@ -35,7 +35,7 @@ def calculate(crs, normalized_img):
         flux = 0
         for coord in cr.coords:
             flux += normalized_img[coord[0]][coord[1]]
-            flux_crs.append(flux)
+        flux_crs.append(flux)
 
     flux_std = std(flux_crs)
     flux_skew = skew(asarray(flux_crs))