diff --git a/share/fsl/sbin/update_fsl_package b/share/fsl/sbin/update_fsl_package
index 501c3d8966aca24aff7a0bc2596b53558294ea46..5df01b9108f2e9e2b1f8026053cb57506163cb8a 100755
--- a/share/fsl/sbin/update_fsl_package
+++ b/share/fsl/sbin/update_fsl_package
@@ -531,9 +531,9 @@ def install_packages(packages : Sequence[Package], dry_run : bool):
 
     print('\nInstalling packages...')
     if dry_run:
-        conda(cmd, False)
-    else:
         print(f'Dry run - would execute {cmd}')
+    else:
+        conda(cmd, False)
 
 
 def parse_args(argv : Optional[Sequence[str]]) -> argparse.Namespace:
@@ -556,7 +556,7 @@ def parse_args(argv : Optional[Sequence[str]]) -> argparse.Namespace:
     parser.add_argument('--username', help=argparse.SUPPRESS)
     parser.add_argument('--password', help=argparse.SUPPRESS)
     parser.add_argument('--verbose',  help=argparse.SUPPRESS, action='store_true')
-    parser.add_argument('--dry-run',  help=argparse.SUPPRESS, action='store_true')
+    parser.add_argument('--dry_run',  help=argparse.SUPPRESS, action='store_true')
 
     args = parser.parse_args(argv)
 
@@ -645,7 +645,7 @@ def main(argv : Sequence[str] = None):
         sys.exit(0)
 
     if confirm_installation(packages, args.yes):
-        install_packages(packages)
+        install_packages(packages, args.dry_run)
     else:
         print('Aborting update')