diff --git a/posix/wordexp-test.c b/posix/wordexp-test.c
index ed1b22308e..cb3f989cba 100644
--- a/posix/wordexp-test.c
+++ b/posix/wordexp-test.c
@@ -183,6 +183,7 @@ struct test_case_struct
     { 0, NULL, "$var", 0, 0, { NULL, }, IFS },
     { 0, NULL, "\"\\n\"", 0, 1, { "\\n", }, IFS },
     { 0, NULL, "", 0, 0, { NULL, }, IFS },
+    { 0, NULL, "${1234567890123456789012}", 0, 0, { NULL, }, IFS },
 
     /* Flags not already covered (testit() has special handling for these) */
     { 0, NULL, "one two", WRDE_DOOFFS, 2, { "one", "two", }, IFS },
diff --git a/posix/wordexp.c b/posix/wordexp.c
index e082d94895..56289503a1 100644
--- a/posix/wordexp.c
+++ b/posix/wordexp.c
@@ -1399,7 +1399,7 @@ envsubst:
   /* Is it a numeric parameter? */
   else if (isdigit (env[0]))
     {
-      int n = atoi (env);
+      unsigned long n = strtoul (env, NULL, 10);
 
       if (n >= __libc_argc)
 	/* Substitute NULL. */