diff --git a/wally/pretty_yaml.py b/wally/pretty_yaml.py
index 2cb5607..afb6375 100644
--- a/wally/pretty_yaml.py
+++ b/wally/pretty_yaml.py
@@ -89,7 +89,8 @@
 
                     if len(val_res) == 1 and \
                        len(key_str + val_res[0]) < width and \
-                       not isinstance(v, dict):
+                       not isinstance(v, dict) and \
+                       not val_res[0].strip().startswith('-'):
                         res.append(key_str + val_res[0])
                     else:
                         res.append(key_str)