diff --git a/src/bitmap.rs b/src/bitmap.rs
index 6a5082a..0b3e034 100644
--- a/src/bitmap.rs
+++ b/src/bitmap.rs
@@ -101,7 +101,7 @@ impl<const PAGE_SIZE: usize> PageAllocator for BitmapPageAllocator<PAGE_SIZE> {
         let align_log2 = align_pow2.trailing_zeros() as usize;
 
         // Check if the base address is aligned to the given PAGE_SIZE.
-        if !Self::is_aligned(base) {
+        if !crate::is_aligned(base, Self::PAGE_SIZE) {
             return Err(AllocError::InvalidParam);
         }
 
@@ -115,7 +115,10 @@ impl<const PAGE_SIZE: usize> PageAllocator for BitmapPageAllocator<PAGE_SIZE> {
     }
 
     fn dealloc_pages(&mut self, pos: usize, num_pages: usize) {
-        assert!(Self::is_aligned(pos), "pos must be aligned to PAGE_SIZE");
+        assert!(
+            crate::is_aligned(pos, Self::PAGE_SIZE),
+            "pos must be aligned to PAGE_SIZE"
+        );
 
         if self
             .inner
@@ -138,12 +141,4 @@ impl<const PAGE_SIZE: usize> PageAllocator for BitmapPageAllocator<PAGE_SIZE> {
     }
 }
 
-impl<const PAGE_SIZE: usize> BitmapPageAllocator<PAGE_SIZE> {
-    /// Checks whether the address has the demanded alignment.
-    ///
-    /// Equivalent to `addr % align == 0`, but the alignment must be a power of two.
-    #[inline]
-    const fn is_aligned(base_addr: usize) -> bool {
-        base_addr & (PAGE_SIZE - 1) == 0
-    }
-}
+impl<const PAGE_SIZE: usize> BitmapPageAllocator<PAGE_SIZE> {}
diff --git a/src/lib.rs b/src/lib.rs
index 7853c28..015a781 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -140,6 +140,14 @@ const fn align_up(pos: usize, align: usize) -> usize {
     (pos + align - 1) & !(align - 1)
 }
 
+/// Checks whether the address has the demanded alignment.
+///
+/// Equivalent to `addr % align == 0`, but the alignment must be a power of two.
+#[inline]
+const fn is_aligned(base_addr: usize, align: usize) -> bool {
+    base_addr & (align - 1) == 0
+}
+
 #[cfg(feature = "allocator_api")]
 mod allocator_api {
     extern crate alloc;