diff --git a/src/util/util.h b/src/util/util.h
new file mode 100644
index 0000000..65ecf94
--- /dev/null
+++ b/src/util/util.h
@@ -0,0 +1,6 @@
+#pragma once
+
+/* Acquires the next power of two of value `x`.
+ * Automatically determines the type (and therefore the width) of `x`.
+ * Explicitly cast `x` to a desired width, if necessary. */
+#define bit_ceil(x) (1 << (sizeof(__typeof__(x)) * 8 - __builtin_clzg(((x) - !!(x)) | 1)))