diff --git a/docs/source/usage.rst b/docs/source/usage.rst
index 4035abe..cf250a7 100644
--- a/docs/source/usage.rst
+++ b/docs/source/usage.rst
@@ -39,8 +39,8 @@ Output Arguments
 ::
 
     Output options:
-      -out prefix           The output file prefix. All file outputs will be stored
-                            as "prefix.dosage" and so on.
+      -out PREFIX           The output file prefix. All file outputs will be stored
+                            as "PREFIX.dosage" and so on.
       -writekey WRITEKEY    Determines the order in which individuals are ordered
                             in the output file based on their order in the
                             corresponding input file. Individuals not in the input