diff --git a/bin/enrgmd b/bin/enrgmd
index aa90fcf7459a37db0fc79f86d448aedc9dc165cd..25d9959d3e38ed317be8d781d0d332f3cb8ca396 100755
--- a/bin/enrgmd
+++ b/bin/enrgmd
@@ -30,7 +30,7 @@ if __name__ == '__main__':
     infile = pathlib.Path(args.input_file)
     try:
         prefix = infile.stem
-        extension = ".".join(infile.suffixes)
+        extension = infile.suffix
     except:
         raise Exception("Unrecognized input file '{}'".format(infile))
         
diff --git a/bin/mrdna b/bin/mrdna
index 41f47a92b464f2e112900296d5abc87e4f1d4744..2ec269964bca2393de2f315a757685da46e1808d 100755
--- a/bin/mrdna
+++ b/bin/mrdna
@@ -42,7 +42,7 @@ if __name__ == '__main__':
     infile = pathlib.Path(args.input_file)
     try:
         prefix = infile.stem
-        extension = ".".join(infile.suffixes)
+        extension = infile.suffix
     except:
         raise Exception("Unrecognized input file '{}'".format(infile))