diff --git a/lucet-runtime/lucet-runtime-internals/src/region/mmap.rs b/lucet-runtime/lucet-runtime-internals/src/region/mmap.rs
index 4ad313e6e..b8542535b 100644
--- a/lucet-runtime/lucet-runtime-internals/src/region/mmap.rs
+++ b/lucet-runtime/lucet-runtime-internals/src/region/mmap.rs
@@ -113,9 +113,11 @@ impl RegionInternal for MmapRegion {
             .pop()
             .ok_or(Error::RegionFull(self.capacity))?;
 
-        if slot.heap as usize % host_page_size() != 0 {
-            lucet_bail!("heap is not page-aligned; this is a bug");
-        }
+        assert_eq!(
+            slot.heap as usize % host_page_size(),
+            0,
+            "heap must be page-aligned"
+        );
 
         for (ptr, len) in [
             // make the stack read/writable