diff --git a/content/data-structures/FenwickTree.h b/content/data-structures/FenwickTree.h
index 7caa5f512..c3becb233 100644
--- a/content/data-structures/FenwickTree.h
+++ b/content/data-structures/FenwickTree.h
@@ -27,7 +27,7 @@ struct FT {
 		int pos = 0;
 		for (int pw = 1 << 25; pw; pw >>= 1) {
 			if (pos + pw <= sz(s) && s[pos + pw-1] < sum)
-				pos += pw, sum -= s[pos-1];
+				sum -= s[(pos+=pw)-1];
 		}
 		return pos;
 	}