diff --git a/src/versionbits.h b/src/versionbits.h
--- a/src/versionbits.h
+++ b/src/versionbits.h
@@ -113,21 +113,21 @@
     void Clear();
 };
 
-/** Get the BIP9 state for a given deployment at the current tip. */
+/** Get the BIP9 state for a given deployment for the block pindexPrev. */
 ThresholdState VersionBitsState(const CBlockIndex *pindexPrev,
                                 const Consensus::Params &params,
                                 Consensus::DeploymentPos pos,
                                 VersionBitsCache &cache);
 /**
- * Get the numerical statistics for the BIP9 state for a given deployment at the
- * current tip.
+ * Get the numerical statistics for a given deployment state for the signalling
+ * period that includes the block after pindexPrev.
  */
 BIP9Stats VersionBitsStatistics(const CBlockIndex *pindexPrev,
                                 const Consensus::Params &params,
                                 Consensus::DeploymentPos pos);
 /**
  * Get the block height at which the BIP9 deployment switched into the state for
- * the block building on the current tip.
+ * the block after pindexPrev.
  */
 int VersionBitsStateSinceHeight(const CBlockIndex *pindexPrev,
                                 const Consensus::Params &params,