diff --git a/bisect.c b/bisect.c
index 135f94ba09..a7862195a9 100644
--- a/bisect.c
+++ b/bisect.c
@@ -1130,16 +1130,6 @@ enum bisect_error bisect_next_all(struct repository *r, const char *prefix)
 	return res;
 }
 
-static inline int log2i(int n)
-{
-	int log2 = 0;
-
-	for (; n > 1; n >>= 1)
-		log2++;
-
-	return log2;
-}
-
 static inline int exp2i(int n)
 {
 	return 1 << n;
@@ -1162,7 +1152,7 @@ int estimate_bisect_steps(int all)
 	if (all < 3)
 		return 0;
 
-	n = log2i(all);
+	n = log2u(all);
 	e = exp2i(n);
 	x = all - e;
 
diff --git a/wrapper.h b/wrapper.h
index 1b2b047ea0..a6b3e1f09e 100644
--- a/wrapper.h
+++ b/wrapper.h
@@ -140,4 +140,22 @@ int csprng_bytes(void *buf, size_t len);
  */
 uint32_t git_rand(void);
 
+/* Provide log2 of the given `size_t`. */
+static inline unsigned log2u(uintmax_t sz)
+{
+	unsigned l = 0;
+
+	/*
+	 * Technically this isn't required, but it helps the compiler optimize
+	 * this to a `bsr` instruction.
+	 */
+	if (!sz)
+		return 0;
+
+	for (; sz; sz >>= 1)
+		l++;
+
+	return l - 1;
+}
+
 #endif /* WRAPPER_H */