diff --git a/src/lib.rs b/src/lib.rs
index 7b84907..6d197d8 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -313,7 +313,7 @@ fn find_contiguous(
     size: usize,
     align_log2: usize,
 ) -> Option<usize> {
-    if capacity < (1 << align_log2) || ba.is_empty() {
+    if align_log2 >= 64 || capacity < (1 << align_log2) || ba.is_empty() {
         return None;
     }
 
@@ -356,7 +356,7 @@ fn check_contiguous(
     size: usize,
     align_log2: usize,
 ) -> bool {
-    if capacity < (1 << align_log2) || ba.is_empty() {
+    if align_log2 >= 64 || capacity < (1 << align_log2) || ba.is_empty() {
         return false;
     }