diff --git a/src/chain.cpp b/src/chain.cpp
index 8d4c4e7deab..ffd58d471d3 100644
--- a/src/chain.cpp
+++ b/src/chain.cpp
@@ -148,3 +148,22 @@ int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& fr
     }
     return sign * r.GetLow64();
 }
+
+/** Find the last common ancestor two blocks have.
+ *  Both pa and pb must be non-NULL. */
+const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
+    if (pa->nHeight > pb->nHeight) {
+        pa = pa->GetAncestor(pb->nHeight);
+    } else if (pb->nHeight > pa->nHeight) {
+        pb = pb->GetAncestor(pa->nHeight);
+    }
+
+    while (pa != pb && pa && pb) {
+        pa = pa->pprev;
+        pb = pb->pprev;
+    }
+
+    // Eventually all chain branches meet at the genesis block.
+    assert(pa == pb);
+    return pa;
+}
diff --git a/src/chain.h b/src/chain.h
index de120d2d75d..c5304b7d6f3 100644
--- a/src/chain.h
+++ b/src/chain.h
@@ -362,6 +362,9 @@ public:
 arith_uint256 GetBlockProof(const CBlockIndex& block);
 /** Return the time it would take to redo the work difference between from and to, assuming the current hashrate corresponds to the difficulty at tip, in seconds. */
 int64_t GetBlockProofEquivalentTime(const CBlockIndex& to, const CBlockIndex& from, const CBlockIndex& tip, const Consensus::Params&);
+/** Find the forking point between two chain tips. */
+const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb);
+
 
 /** Used to marshal pointers into hashes for db storage. */
 class CDiskBlockIndex : public CBlockIndex
diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 8fc6f6f95e9..4d832f37113 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -452,25 +452,6 @@ bool PeerHasHeader(CNodeState *state, const CBlockIndex *pindex)
     return false;
 }
 
-/** Find the last common ancestor two blocks have.
- *  Both pa and pb must be non-NULL. */
-const CBlockIndex* LastCommonAncestor(const CBlockIndex* pa, const CBlockIndex* pb) {
-    if (pa->nHeight > pb->nHeight) {
-        pa = pa->GetAncestor(pb->nHeight);
-    } else if (pb->nHeight > pa->nHeight) {
-        pb = pb->GetAncestor(pa->nHeight);
-    }
-
-    while (pa != pb && pa && pb) {
-        pa = pa->pprev;
-        pb = pb->pprev;
-    }
-
-    // Eventually all chain branches meet at the genesis block.
-    assert(pa == pb);
-    return pa;
-}
-
 /** Update pindexLastCommonBlock and add not-in-flight missing successors to vBlocks, until it has
  *  at most count entries. */
 void FindNextBlocksToDownload(NodeId nodeid, unsigned int count, std::vector<const CBlockIndex*>& vBlocks, NodeId& nodeStaller, const Consensus::Params& consensusParams) {