Typo (env -0 was checking the flag wrong).
diff --git a/toys/posix/env.c b/toys/posix/env.c
index 041c6d9..2de8f69 100644
--- a/toys/posix/env.c
+++ b/toys/posix/env.c
@@ -56,5 +56,5 @@
   }
 
   if (environ) for (ev = environ; *ev; ev++)
-    xprintf("%s%c", *ev, '\n'*!(toys.optflags*FLAG_0));
+    xprintf("%s%c", *ev, '\n'*!(toys.optflags&FLAG_0));
 }