diff --git a/doc/release-notes.md b/doc/release-notes.md
--- a/doc/release-notes.md
+++ b/doc/release-notes.md
@@ -6,3 +6,4 @@
  - Support for Nov 2019 upgrade features, as detailed at https://github.com/bitcoincashorg/bitcoincash.org/blob/master/spec/2019-11-15-upgrade.md
     - Schnorr signatures for OP_CHECKMULTISIG(VERIFY): https://github.com/bitcoincashorg/bitcoincash.org/blob/master/spec/2019-11-15-schnorrmultisig.md
     - Enforce MINIMALDATA in script: https://github.com/bitcoincashorg/bitcoincash.org/blob/master/spec/2019-11-15-minimaldata.md
+ - Bump automatic replay protection to May 2020 upgrade.
diff --git a/src/chainparams.cpp b/src/chainparams.cpp
--- a/src/chainparams.cpp
+++ b/src/chainparams.cpp
@@ -124,6 +124,9 @@
         // Nov 15, 2019 12:00:00 UTC protocol upgrade
         consensus.gravitonActivationTime = 1573819200;
 
+        // May 15, 2020 12:00:00 UTC protocol upgrade
+        consensus.phononActivationTime = 1589544000;
+
         /**
          * The message start string is designed to be unlikely to occur in
          * normal data. The characters are rarely used upper ASCII, not valid as
@@ -287,6 +290,9 @@
         // Nov 15, 2019 12:00:00 UTC protocol upgrade
         consensus.gravitonActivationTime = 1573819200;
 
+        // May 15, 2020 12:00:00 UTC protocol upgrade
+        consensus.phononActivationTime = 1589544000;
+
         diskMagic[0] = 0x0b;
         diskMagic[1] = 0x11;
         diskMagic[2] = 0x09;
@@ -402,6 +408,9 @@
         // Nov 15, 2019 12:00:00 UTC protocol upgrade
         consensus.gravitonActivationTime = 1573819200;
 
+        // May 15, 2020 12:00:00 UTC protocol upgrade
+        consensus.phononActivationTime = 1589544000;
+
         diskMagic[0] = 0xfa;
         diskMagic[1] = 0xbf;
         diskMagic[2] = 0xb5;
diff --git a/src/consensus/params.h b/src/consensus/params.h
--- a/src/consensus/params.h
+++ b/src/consensus/params.h
@@ -38,6 +38,8 @@
     int magneticAnomalyHeight;
     /** Unix time used for MTP activation of Nov 15 2019 12:00:00 UTC upgrade */
     int gravitonActivationTime;
+    /** Unix time used for MTP activation of 15 May 2020 12:00:00 UTC upgrade */
+    int phononActivationTime;
     /** Proof of work parameters */
     uint256 powLimit;
     bool fPowAllowMinDifficultyBlocks;
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -434,7 +434,7 @@
     return nMedianTimePast >=
            gArgs.GetArg(
                "-replayprotectionactivationtime",
-               config.GetChainParams().GetConsensus().gravitonActivationTime);
+               config.GetChainParams().GetConsensus().phononActivationTime);
 }
 
 static bool IsReplayProtectionEnabled(const Config &config,