Index: src/script/interpreter.cpp
===================================================================
--- src/script/interpreter.cpp
+++ src/script/interpreter.cpp
@@ -315,6 +315,7 @@
     }
     int nOpCount = 0;
     bool fRequireMinimal = (flags & SCRIPT_VERIFY_MINIMALDATA) != 0;
+    bool fEnabledOpCodes0 = (flags & SCRIPT_ENABLE_OPCODES0) != 0;
 
     try {
         while (pc < pend) {
@@ -335,10 +336,24 @@
                 return set_error(serror, SCRIPT_ERR_OP_COUNT);
             }
 
-            if (opcode == OP_INVERT || opcode == OP_2MUL || opcode == OP_2DIV ||
-                opcode == OP_MUL || opcode == OP_LSHIFT || opcode == OP_RSHIFT) {
-                // Disabled opcodes.
-                return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
+            // May 15 2018 HF activates AND, OR, XOR, DIV, MOD, CAT, and SPLIT
+            if (fEnabledOpCodes0) {
+                if (opcode == OP_INVERT || opcode == OP_2MUL || opcode == OP_2DIV ||
+                    opcode == OP_MUL || opcode == OP_LSHIFT || opcode == OP_RSHIFT) {
+                    // Disabled opcodes.
+                    return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
+                }
+            }
+            else {
+                if (opcode == OP_CAT || opcode == OP_SPLIT || opcode == OP_BIN2NUM ||
+                    opcode == OP_NUM2BIN || opcode == OP_INVERT || opcode == OP_AND ||
+                    opcode == OP_OR || opcode == OP_XOR || opcode == OP_2MUL ||
+                    opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_DIV ||
+                    opcode == OP_MOD || opcode == OP_LSHIFT ||
+                    opcode == OP_RSHIFT) {
+                    // Disabled opcodes.
+                    return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
+                }
             }
 
             if (fExec && 0 <= opcode && opcode <= OP_PUSHDATA4) {
Index: src/validation.cpp
===================================================================
--- src/validation.cpp
+++ src/validation.cpp
@@ -1897,7 +1897,7 @@
     // Once the the 15 May 2018 hardfork activates we may begin using new opcodes.
     // Therefore script flags need to be passed to the interpreter allowing this.
     if (IsForkMay152018Enabled(config, pindex->pprev)) {
-        //flags |= SCRIPT_ENABLE_OPCODES0; // Note this will be uncommented in a later commit
+        flags |= SCRIPT_ENABLE_OPCODES0;
     }
 
     return flags;