Index: src/script/interpreter.cpp
===================================================================
--- src/script/interpreter.cpp
+++ src/script/interpreter.cpp
@@ -337,8 +337,8 @@
 
             if (opcode == OP_CAT || opcode == OP_SUBSTR || opcode == OP_LEFT ||
                 opcode == OP_RIGHT || opcode == OP_INVERT || opcode == OP_2MUL ||
-                opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_MOD ||
-                opcode == OP_LSHIFT || opcode == OP_RSHIFT) {
+                opcode == OP_2DIV || opcode == OP_MUL || opcode == OP_LSHIFT ||
+                opcode == OP_RSHIFT) {
                 // Disabled opcodes.
                 return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
             }
@@ -894,6 +894,7 @@
                     case OP_ADD:
                     case OP_SUB:
                     case OP_DIV:
+                    case OP_MOD:
                     case OP_BOOLAND:
                     case OP_BOOLOR:
                     case OP_NUMEQUAL:
@@ -931,6 +932,14 @@
                                 }
                                 bn = bn1 / bn2;
                                 break;
+                            case OP_MOD:
+                                // 2nd operand must not be 0
+                                if (bn2 == 0) {
+                                    return set_error(
+                                        serror, SCRIPT_ERR_MOD_BY_ZERO);
+                                }
+                                bn = bn1 % bn2;
+                                break;
 
                             case OP_BOOLAND:
                                 bn = (bn1 != bnZero && bn2 != bnZero);
Index: src/script/script.h
===================================================================
--- src/script/script.h
+++ src/script/script.h
@@ -279,6 +279,12 @@
     inline CScriptNum operator/(const CScriptNum &rhs) const {
         return operator/(rhs.m_value);
     }
+    inline CScriptNum operator%(const int64_t &rhs) const {
+        return CScriptNum(m_value % rhs);
+    }
+    inline CScriptNum operator%(const CScriptNum &rhs) const {
+        return operator%(rhs.m_value);
+    }
 
     inline CScriptNum &operator+=(const CScriptNum &rhs) {
         return operator+=(rhs.m_value);
Index: src/script/script_error.h
===================================================================
--- src/script/script_error.h
+++ src/script/script_error.h
@@ -35,6 +35,7 @@
     SCRIPT_ERR_UNBALANCED_CONDITIONAL,
     SCRIPT_ERR_INVALID_BITWISE_OPERATION,
     SCRIPT_ERR_DIV_BY_ZERO,
+    SCRIPT_ERR_MOD_BY_ZERO,
 
     /* CHECKLOCKTIMEVERIFY and CHECKSEQUENCEVERIFY */
     SCRIPT_ERR_NEGATIVE_LOCKTIME,
Index: src/script/script_error.cpp
===================================================================
--- src/script/script_error.cpp
+++ src/script/script_error.cpp
@@ -50,6 +50,8 @@
             return "Invalid bitwise operation (check length of inputs)";
         case SCRIPT_ERR_DIV_BY_ZERO:
             return "Invalid division operation";
+        case SCRIPT_ERR_MOD_BY_ZERO:
+            return "Invalid modulo operation";
         case SCRIPT_ERR_NEGATIVE_LOCKTIME:
             return "Negative locktime";
         case SCRIPT_ERR_UNSATISFIED_LOCKTIME: