diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -1231,6 +1231,45 @@
                             // Disabled opcodes.
                             return set_error(serror, SCRIPT_ERR_DISABLED_OPCODE);
                         }
+                        // (in size -- out)
+                        if (stack.size() < 2) {
+                            return set_error(
+                                serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
+                        }
+                        CScriptNum num(stacktop(-2), fRequireMinimal);
+                        int64_t size = CScriptNum(stacktop(-1), fRequireMinimal).getint();
+                        if (size < 1 || static_cast<uint64_t>(size) > CScriptNum::nDefaultMaxNumSize) {
+                            return set_error(
+                                serror, SCRIPT_ERR_INVALID_NUM2BIN_OPERATION);
+                        }
+                        // Produces a byte vector of num and check if input size
+                        // is valid
+                        valtype vchNum = num.getvch();
+                        if (size < vchNum.size()) {
+                            return set_error(
+                                serror, SCRIPT_ERR_INVALID_NUM2BIN_OPERATION);
+                        }
+                        // Initialize byte vector for result
+                        valtype result;
+                        result.reserve(size);
+                        bool neg{false};
+                        // Avoid negative zero
+                        if (!vchNum.empty()) {
+                            neg = *vchNum.rbegin() & 0x80;
+                            *vchNum.rbegin() &= ~0x80;
+                        }
+                        // Pad result to declared input size
+                        size_t pad = size - vchNum.size();
+                        for (uint8_t i = 0; i < pad; ++i) {
+                            result.push_back(0);
+                        }
+                        for (auto i = vchNum.rbegin(); i != vchNum.rend(); ++i) {
+                            result.push_back(*i);
+                        }
+                        if (neg) *result.begin() |= 0x80;
+                        stack.pop_back();
+                        stack.pop_back();
+                        stack.push_back(result);
                     } break;
 
                     default: