diff --git a/vmbase/src/entry.rs b/vmbase/src/entry.rs
index 892dc9f..bb5ccef 100644
--- a/vmbase/src/entry.rs
+++ b/vmbase/src/entry.rs
@@ -15,13 +15,13 @@
 //! Rust entry point.
 
 use crate::{
-    bionic, console, heap,
-    hyp::{self, MMIO_GUARD_GRANULE_SIZE},
-    logger,
+    bionic, console, heap, hyp, logger,
+    memory::{page_4kb_of, SIZE_16KB, SIZE_4KB},
     power::{reboot, shutdown},
     rand,
 };
 use core::mem::size_of;
+use static_assertions::const_assert_eq;
 
 fn try_console_init() -> Result<(), hyp::Error> {
     console::init();
@@ -31,8 +31,19 @@
 
         // TODO(ptosi): Use MmioSharer::share() to properly track this MMIO_GUARD_MAP.
         //
-        // MmioSharer only supports MMIO_GUARD_GRANULE_SIZE so fail early here if needed.
-        assert_eq!(mmio_guard.granule()?, MMIO_GUARD_GRANULE_SIZE);
+        // The following call shares the UART but also anything else present in 0..granule.
+        //
+        // For 4KiB, that's only the UARTs. For 16KiB, it also covers the RTC and watchdog but, as
+        // neither is used by vmbase clients (and as both are outside of the UART page), they
+        // will never have valid stage-1 mappings to those devices. As a result, this
+        // MMIO_GUARD_MAP isn't affected by the granule size in any visible way. Larger granule
+        // sizes will need to be checked separately, if needed.
+        assert!({
+            let granule = mmio_guard.granule()?;
+            granule == SIZE_4KB || granule == SIZE_16KB
+        });
+        // Validate the assumption above by ensuring that the UART is not moved to another page:
+        const_assert_eq!(page_4kb_of(console::BASE_ADDRESS), 0);
         mmio_guard.map(console::BASE_ADDRESS)?;
     }