diff --git a/src/index/base.cpp b/src/index/base.cpp
--- a/src/index/base.cpp
+++ b/src/index/base.cpp
@@ -66,7 +66,8 @@
     return true;
 }
 
-static const CBlockIndex *NextSyncBlock(const CBlockIndex *pindex_prev) {
+static const CBlockIndex *NextSyncBlock(const CBlockIndex *pindex_prev)
+    EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
     AssertLockHeld(cs_main);
 
     if (!pindex_prev) {
diff --git a/src/validation.h b/src/validation.h
--- a/src/validation.h
+++ b/src/validation.h
@@ -400,7 +400,7 @@
 /**
  * Update the chain tip based on database information.
  */
-bool LoadChainTip(const Config &config);
+bool LoadChainTip(const Config &config) EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Unload database information.
@@ -638,7 +638,8 @@
 
 /** Find the last common block between the parameter chain and a locator. */
 CBlockIndex *FindForkInGlobalIndex(const CChain &chain,
-                                   const CBlockLocator &locator);
+                                   const CBlockLocator &locator)
+    EXCLUSIVE_LOCKS_REQUIRED(cs_main);
 
 /**
  * Mark a block as precious and reorganize.