diff --git a/env.c b/env.c
index e1ab50bf8..58c64adaa 100644
--- a/env.c
+++ b/env.c
@@ -654,7 +654,7 @@ void env_init()
 	{
 		wchar_t *nshlvl, **end_nshlvl;
 		/* add an extra space for digit dump (9+1=10) */
-		size_t i =  wcslen( shlvl ) + 2;
+		size_t i =  wcslen( shlvl ) + 2 * sizeof(wchar_t);
 		nshlvl = malloc(i);
 		end_nshlvl = calloc( 1, sizeof(nshlvl) );
 		if ( nshlvl && swprintf( nshlvl, i,