diff --git a/lib/std/core/dstring.c3 b/lib/std/core/dstring.c3
index fec99bf33..df4035453 100644
--- a/lib/std/core/dstring.c3
+++ b/lib/std/core/dstring.c3
@@ -1,5 +1,5 @@
 module std::core::dstring;
-import std::io;
+import std::io, std::math;
 
 <*
  The DString offers a dynamic string builder.
@@ -648,7 +648,7 @@ fn void DString.reserve(&self, usz addition)
 	if (data.capacity >= len) return;
 	usz new_capacity = data.capacity * 2;
 	if (new_capacity < MIN_CAPACITY) new_capacity = MIN_CAPACITY;
-	while (new_capacity < len) new_capacity *= 2;
+	if (new_capacity < len) new_capacity = math::next_power_of_2(len);
 	data.capacity = new_capacity;
 	*self = (DString)allocator::realloc(data.allocator, data, StringData.sizeof + new_capacity);
 }
diff --git a/lib/std/math/math.c3 b/lib/std/math/math.c3
index 7c7cf1cc9..f39628262 100644
--- a/lib/std/math/math.c3
+++ b/lib/std/math/math.c3
@@ -997,11 +997,29 @@ macro bool is_power_of_2(x)
 	return x != 0 && (x & (x - 1)) == 0;
 }
 
+<*
+ Returns the next power of two that is greater than or equal to x.
+
+ @require types::is_int($typeof(x)) : "Input must be an integer type"
+ @require x >= 0 : "Input must be non-negative"
+*>
 macro next_power_of_2(x)
 {
-	$typeof(x) y = 1;
-	while (y < x) y += y;
-	return y;
+	if (x <= 1) return 1;
+	if (x == 2) return 2;
+
+	$typeof(x) v = x - 1;
+
+	v |= v >> 1;
+	v |= v >> 2;
+	v |= v >> 4;
+
+	$if ($sizeof(x) >= 2):  v |= v >> 8;  $endif;
+	$if ($sizeof(x) >= 4):  v |= v >> 16; $endif;
+	$if ($sizeof(x) >= 8):  v |= v >> 32; $endif;
+	$if ($sizeof(x) >= 16): v |= v >> 64; $endif;
+
+	return v + 1;
 }
 
 macro equals_vec(v1, v2) @private