diff --git a/stand/common/gfx_fb.c b/stand/common/gfx_fb.c
--- a/stand/common/gfx_fb.c
+++ b/stand/common/gfx_fb.c
@@ -242,6 +242,7 @@
 {
 	const char *ptr;
 	char env[10];
+	int eflags = EV_VOLATILE | EV_NOKENV;
 	bool from_env = false;
 
 	ptr = getenv(envname);
@@ -257,10 +258,16 @@
 		if (unsetenv(envname) != 0)
 			return (true);
 		from_env = true;
+
+		/*
+		 * If we're carrying over an existing value, we *do* want that
+		 * to propagate to the kenv.
+		 */
+		eflags &= ~EV_NOKENV;
 	}
 
 	snprintf(env, sizeof(env), "%d", *cattr);
-	env_setenv(envname, EV_VOLATILE, env, sethook, unsethook);
+	env_setenv(envname, eflags, env, sethook, unsethook);
 
 	return (from_env);
 }
diff --git a/stand/common/modinfo.c b/stand/common/modinfo.c
--- a/stand/common/modinfo.c
+++ b/stand/common/modinfo.c
@@ -172,6 +172,8 @@
 
 	/* Traverse the environment. */
 	for (ep = environ; ep != NULL; ep = ep->ev_next) {
+		if ((ep->ev_flags & EV_NOKENV) != 0)
+			continue;
 		len = strlen(ep->ev_name);
 		if ((size_t)archsw.arch_copyin(ep->ev_name, addr, len) != len)
 			break;
diff --git a/stand/libsa/environment.c b/stand/libsa/environment.c
--- a/stand/libsa/environment.c
+++ b/stand/libsa/environment.c
@@ -65,6 +65,17 @@
 	struct env_var	*ev, *curr, *last;
 
 	if ((ev = env_getenv(name)) != NULL) {
+		/*
+		 * If the new value doesn't have NOKENV set, we'll drop the flag
+		 * if it's set on the entry so that the override propagates
+		 * correctly.  We do this *before* sending it to the hook in
+		 * case the hook declines to operate on it (e.g., because the
+		 * value matches what was already set) -- we would still want
+		 * the explicitly set value to propagate.
+		 */
+		if (!(flags & EV_NOKENV))
+			ev->ev_flags &= ~EV_NOKENV;
+
 		/*
 		 * If there's a set hook, let it do the work
 		 * (unless we are working for one already).
@@ -77,7 +88,6 @@
 			free(ev->ev_value);
 		ev->ev_value = NULL;
 		ev->ev_flags &= ~EV_DYNAMIC;
-
 	} else {
 
 		/*
@@ -123,12 +133,13 @@
 	/* If we have a new value, use it */
 	if (flags & EV_VOLATILE) {
 		ev->ev_value = strdup(value);
-		ev->ev_flags |= EV_DYNAMIC;
+		flags |= EV_DYNAMIC;
 	} else {
 		ev->ev_value = (char *)value;
-		ev->ev_flags |= flags & EV_DYNAMIC;
 	}
 
+	ev->ev_flags |= flags & (EV_DYNAMIC | EV_NOKENV);
+
 	return (0);
 }
 
diff --git a/stand/libsa/stand.h b/stand/libsa/stand.h
--- a/stand/libsa/stand.h
+++ b/stand/libsa/stand.h
@@ -352,6 +352,7 @@
 #define EV_DYNAMIC	(1<<0)		/* value was dynamically allocated, free if changed/unset */
 #define EV_VOLATILE	(1<<1)		/* value is volatile, make a copy of it */
 #define EV_NOHOOK	(1<<2)		/* don't call hook when setting */
+#define EV_NOKENV	(1<<3)		/* don't add to kenv (loader-only) */
 
 struct env_var;
 typedef char	*(ev_format_t)(struct env_var *ev);