diff --git a/src/pbc_disassemble.c b/src/pbc_disassemble.c
index 9970a4f..b6efbd8 100644
--- a/src/pbc_disassemble.c
+++ b/src/pbc_disassemble.c
@@ -75,7 +75,8 @@ static struct longopt_opt_decl options[] = {
 #if TRACE_PACKFILE
     { 'D', 'D', OPTION_required_FLAG, { "--debug" } },
 #endif
-    { 'o', 'o', OPTION_required_FLAG, { "--output" } }
+    { 'o', 'o', OPTION_required_FLAG, { "--output" } },
+    {  0 ,  0,  0,                    { NULL } }
 };
 
 /*