diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -943,6 +943,12 @@
                                     // Disabled opcode.
                                     return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
                                 }
+                                // 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:
diff --git a/src/script/script.h b/src/script/script.h
--- a/src/script/script.h
+++ b/src/script/script.h
@@ -288,6 +288,12 @@
     inline CScriptNum &operator-=(const CScriptNum &rhs) {
         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 int64_t &rhs) const {
         return CScriptNum(m_value & rhs);