diff --git a/compiler/msg/errorf.msg b/compiler/msg/errorf.msg
index 13238959ac..cf40eacee8 100644
--- a/compiler/msg/errorf.msg
+++ b/compiler/msg/errorf.msg
@@ -1636,7 +1636,7 @@ unit_u_check_time=10037_U_PPU Check file $1 time $2
 #
 #  Options
 #
-option_usage=11000_$1 [options] <inputfile> [options]
+option_usage=11000_O_$1 [options] <inputfile> [options]
 # BeginOfTeX
 %
 % \section{Command-line handling errors}
diff --git a/compiler/msg/errorhe.msg b/compiler/msg/errorhe.msg
index 52e109c046..59488fd86f 100644
--- a/compiler/msg/errorhe.msg
+++ b/compiler/msg/errorhe.msg
@@ -2010,7 +2010,7 @@ unit_u_skipping_reresolving_unit=10059_U_Skipping re-resolving unit $1, still lo
 #
 # 11039 is the last used one
 #
-option_usage=11000_$1 [options] <inputfile> [options]
+option_usage=11000_O_$1 [options] <inputfile> [options]
 # BeginOfTeX
 %
 % \section{Command-line handling errors}