diff --git a/histoqc/ClassificationModule.py b/histoqc/ClassificationModule.py
index 44273c9..9567a49 100644
--- a/histoqc/ClassificationModule.py
+++ b/histoqc/ClassificationModule.py
@@ -184,7 +184,7 @@ def byExampleWithFeatures(s, params):
                 # convert grayscale images into binary images if images are not binary format 
                 if mask.dtype.kind != 'b':
                     # warning log
-                    msg = f"Mask file '{ex[1]}' is not a binary image"
+                    msg = f"Mask file '{ex[1]}' is not a binary image. Automatically converting to binary..."
                     logging.warning(s['filename'] + ' - ' + msg)
                     s["warnings"].append(msg)
                     # convert to binary
diff --git a/histoqc/DeconvolutionModule.py b/histoqc/DeconvolutionModule.py
index 8c85732..dbb41f1 100644
--- a/histoqc/DeconvolutionModule.py
+++ b/histoqc/DeconvolutionModule.py
@@ -23,9 +23,9 @@ def separateStains(s, params):
         sys.exit(1)
         return
 
-    stain_matrix = getattr(sys.modules[__name__], stain, "")
+    stain_matrix = getattr(sys.modules[__name__], stain, None)
 
-    if stain_matrix == "":
+    if stain_matrix is None:
         logging.error(f"{s['filename']} - Unknown stain matrix specified in DeconolutionModule.separateStains")
         sys.exit(1)
         return