diff --git a/cobj/cobj.c b/cobj/cobj.c
index ad750588..aa226c7e 100644
--- a/cobj/cobj.c
+++ b/cobj/cobj.c
@@ -811,6 +811,7 @@ static void cobc_print_usage(void) {
   puts(_("  -conf=<file>                      User defined dialect "
          "configuration - See -std="));
   puts(_("  --list-reserved                   Display reserved words"));
+  puts(_("  -ext <extension>                  Add default file extension"));
   puts(
       _("  -assign_external                  Set the file assign to external"));
   puts(_("  -constant                         Define <name> to <value> for $IF "
diff --git a/tests/Makefile.am b/tests/Makefile.am
index a26738a6..96e7d7d0 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -149,6 +149,7 @@ command_line_options_DEPENDENCIES = \
 	command-line-options.src/t.at \
 	command-line-options.src/B.at \
 	command-line-options.src/list-reserved.at \
+	command-line-options.src/ext.at \
 	command-line-options.src/assign_external.at \
 	command-line-options.src/Wobsolete-Warchaic.at \
 	command-line-options.src/Wredefinition.at \
diff --git a/tests/Makefile.in b/tests/Makefile.in
index 7dc83d5b..3f93a17d 100644
--- a/tests/Makefile.in
+++ b/tests/Makefile.in
@@ -690,6 +690,7 @@ command_line_options_DEPENDENCIES = \
 	command-line-options.src/t.at \
 	command-line-options.src/B.at \
 	command-line-options.src/list-reserved.at \
+	command-line-options.src/ext.at \
 	command-line-options.src/assign_external.at \
 	command-line-options.src/Wobsolete-Warchaic.at \
 	command-line-options.src/Wredefinition.at \
diff --git a/tests/command-line-options.at b/tests/command-line-options.at
index f9af0506..c5e4f608 100644
--- a/tests/command-line-options.at
+++ b/tests/command-line-options.at
@@ -7,6 +7,7 @@ m4_include([C.at])
 m4_include([t.at])
 m4_include([B.at])
 m4_include([list-reserved.at])
+m4_include([ext.at])
 m4_include([assign_external.at])
 m4_include([java-package.at])
 m4_include([Wobsolete-Warchaic.at])
diff --git a/tests/command-line-options.src/ext.at b/tests/command-line-options.src/ext.at
new file mode 100644
index 00000000..5dfa49a4
--- /dev/null
+++ b/tests/command-line-options.src/ext.at
@@ -0,0 +1,22 @@
+AT_SETUP([-ext])
+
+AT_DATA([prog.cbl],
+[       IDENTIFICATION   DIVISION.
+       PROGRAM-ID.      prog.
+       PROCEDURE        DIVISION.
+           COPY "sub".
+           STOP RUN.
+])
+
+AT_DATA([sub.abc563788BBN],
+[           DISPLAY "sub".
+])
+
+AT_CHECK([${COBJ} -ext abc563788BBN prog.cbl])
+AT_CHECK([java prog], [0],
+[sub
+])
+
+AT_CHECK([${COBJ} --help | grep '\-ext' > /dev/null], [0])
+
+AT_CLEANUP