diff --git a/src/core/common.hpp b/src/core/common.hpp
index 6fa5f89f..9ca6b53d 100644
--- a/src/core/common.hpp
+++ b/src/core/common.hpp
@@ -20,14 +20,3 @@ using m128 = __m128i;
 #define INT128_MAX ((u128)0x7FFF'FFFF'FFFF'FFFF << 64) | 0xFFFF'FFFF'FFFF'FFFF
 #define INT128_MIN (-INT128_MAX - 1LL)
 
-template <u8 start, u8 end>
-using BitSliceType =
-std::conditional<(end - start) <= 7, u8,
-  std::conditional<(end - start) <= 15, u16,
-    std::conditional<(end - start) <= 31, u32,
-      std::conditional<(end - start) <= 63, u64,
-        std::conditional<(end - start) <= 127, u128, u128>
-      >
-    >
-  >
->;
diff --git a/src/core/util.hpp b/src/core/util.hpp
index 27b1902f..cc44dc7f 100644
--- a/src/core/util.hpp
+++ b/src/core/util.hpp
@@ -1,12 +1,32 @@
 #pragma once
 #include <common.hpp>
 #include <type_traits>
+#include <cassert>
 
 namespace natsukashii::util {
+template <u8 start, u8 end>
+using BitSliceType =
+typename std::conditional<(end - start) <= 7, u8,
+  typename std::conditional<(end - start) <= 15, u16,
+    typename std::conditional<(end - start) <= 31, u32,
+      typename std::conditional<(end - start) <= 63, u64,
+        typename std::conditional<(end - start) <= 127, u128, void>::type
+      >::type
+    >::type
+  >::type
+>::type;
+
 template <u8 start, u8 end, typename T>
 BitSliceType<start, end> BitSlice(const T& num) {
-  static_assert(end - start > 127);
-  static_assert(end - start > sizeof(T));
-  return (num >> start) & ((1 << end) - 1);
+  static_assert(end < (sizeof(T) * 8) && start < (sizeof(T) * 8));
+  constexpr auto correctedEnd = end == (sizeof(T) * 8) - 1 ? end : end + 1;
+  return (num >> start) & ((1 << correctedEnd) - 1);
+}
+
+template <typename T>
+T BitSlice(const T& num, int start, int end) {
+  assert(end < (sizeof(T) * 8) && start < (sizeof(T) * 8));
+  auto correctedEnd = end == (sizeof(T) * 8) - 1 ? end : end + 1;
+  return (num >> start) & ((1 << correctedEnd) - 1);
 }
 }