diff --git a/fastqwiper/fastq_gather.py b/fastqwiper/fastq_gather.py
index eef4c67..57dc433 100644
--- a/fastqwiper/fastq_gather.py
+++ b/fastqwiper/fastq_gather.py
@@ -33,6 +33,7 @@ def files_choices(choices, fname):
 
             if ext not in choices:
                 parser.error(f"File '{fname}' doesn't end with one of {choices}")
+                raise ValueError(f"File '{fname}' doesn't end with one of {choices}")
             return fname
 
         parser.add_argument(
diff --git a/fastqwiper/fastq_scatter.py b/fastqwiper/fastq_scatter.py
index 0becc40..7f81554 100644
--- a/fastqwiper/fastq_scatter.py
+++ b/fastqwiper/fastq_scatter.py
@@ -35,6 +35,7 @@ def file_choices(choices, fname):
             if ext not in choices:
                 parser.error(
                     f"File '{fname}' doesn't end with one of {choices}")
+                raise ValueError(f"File '{fname}' doesn't end with one of {choices}")
             return fname
 
         parser.add_argument("-f", "--fastq", type=lambda s: file_choices((e.name.lower().replace("_", ".")