diff --git a/shell/shell_common.h b/shell/shell_common.h
index 993ed59..a82535c 100644
--- a/shell/shell_common.h
+++ b/shell/shell_common.h
@@ -24,6 +24,8 @@
 extern const char defifsvar[] ALIGN1; /* "IFS= \t\n" */
 #define defifs (defifsvar + 4)
 
+extern const char defoptindvar[] ALIGN1; /* "OPTIND=1" */
+
 int FAST_FUNC is_well_formed_var_name(const char *s, char terminator);
 
 /* Builtins */