diff --git a/src/validation.cpp b/src/validation.cpp
index 91531b4bef..73d39f8193 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -283,7 +283,8 @@ namespace {
 
 CBlockIndex* FindForkInGlobalIndex(const CChain& chain, const CBlockLocator& locator)
 {
-    // Find the first block the caller has in the main chain
+    // Find the latest block common to locator and chain - we expect that
+    // locator.vHave is sorted descending by height.
     for (const uint256& hash : locator.vHave) {
         BlockMap::iterator mi = mapBlockIndex.find(hash);
         if (mi != mapBlockIndex.end())