Index: src/script/interpreter.cpp
===================================================================
--- src/script/interpreter.cpp
+++ src/script/interpreter.cpp
@@ -88,7 +88,7 @@
     if (fEnabledOpCodesMagnetic) {
         switch (opcode) {
             case OP_INVERT:
-                return true;
+                return false;
 
             case OP_MUL:
                 return true;
@@ -1234,6 +1234,19 @@
                         }
                     } break;
 
+                    case OP_INVERT: {
+                        // (x -- out)
+                        if (stack.size() < 1) {
+                            return set_error(
+                                serror, SCRIPT_ERR_INVALID_STACK_OPERATION);
+                        }
+
+                        valtype &x = stacktop(-1);
+                        for (size_t i = 0; i < x.size(); i++) {
+                            x[i] = ~x[i];
+                        }
+                    } break;
+
                     default:
                         return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
                 }
Index: src/test/data/script_tests.json
===================================================================
--- src/test/data/script_tests.json
+++ src/test/data/script_tests.json
@@ -928,8 +928,8 @@
 ["NOP", "SIZE 1", "P2SH,STRICTENC", "INVALID_STACK_OPERATION"],
 
 ["Disabled opcodes"],
-["'abc'", "IF INVERT ELSE 1 ENDIF", "P2SH,STRICTENC", "DISABLED_OPCODE", "INVERT disabled"],
-["'abc'", "IF INVERT ELSE 1 ENDIF", "P2SH,STRICTENC,MAGNETIC_OPCODES", "DISABLED_OPCODE", "INVERT disabled"],
+["'abc' 0", "IF INVERT ELSE 1 ENDIF", "P2SH,STRICTENC", "DISABLED_OPCODE", "INVERT disabled"],
+["'abc' 0", "IF INVERT ELSE 1 ENDIF", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT enabled"],
 ["2 0 IF 2MUL ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "2MUL disabled"],
 ["2 0 IF 2DIV ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "2DIV disabled"],
 ["2 2 0 IF MUL ELSE 1 ENDIF", "NOP", "P2SH,STRICTENC", "DISABLED_OPCODE", "MUL disabled"],
@@ -982,6 +982,16 @@
 ["2 1 RSHIFT", "1 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "DISABLED_OPCODE", "disabled"],
 
 ["INVERT"],
+["", "INVERT", "P2SH,STRICTENC,MAGNETIC_OPCODES", "INVALID_STACK_OPERATION", "INVERT, invalid parameter count"],
+["0x0100", "INVERT 0x01FF EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, simple"],
+["0x01FF", "INVERT 0x0100 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, simple"],
+["0x00", "INVERT 0x00 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, empty"],
+["0x020F0F", "INVERT 0x02F0F0 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 2 bytes"],
+["0x03FF0000", "INVERT 0x0300FFFF EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 3 bytes"],
+["0x0300FFFF", "INVERT 0x03FF0000 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 3 bytes"],
+["0x03FFFFFF", "INVERT 0x03000000 EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 3 bytes"],
+["0x03801234", "INVERT 0x037FEDCB EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 3 bytes"],
+["0x088012348012341234", "INVERT 0x087FEDCB7FEDCBEDCB EQUAL", "P2SH,STRICTENC,MAGNETIC_OPCODES", "OK", "INVERT, 8 bytes"],
 
 ["Arithmetic Opcodes"],
 ["DIV"],
Index: src/test/opcode_tests.cpp
===================================================================
--- src/test/opcode_tests.cpp
+++ src/test/opcode_tests.cpp
@@ -74,6 +74,11 @@
     CheckTestResultForAllFlags({a, b}, CScript() << op, {expected});
 }
 
+static void CheckUnaryOp(const valtype &a, opcodetype op,
+                         const valtype &expected) {
+    CheckTestResultForAllFlags({a}, CScript() << op, {expected});
+}
+
 static valtype NegativeValtype(const valtype &v) {
     valtype r(v);
     if (r.size() > 0) {
@@ -395,6 +400,14 @@
     CheckAllBitwiseOpErrors({b, {}}, SCRIPT_ERR_INVALID_OPERAND_SIZE);
 }
 
+BOOST_AUTO_TEST_CASE(invert_test) {
+    CheckUnaryOp({}, OP_INVERT, {});
+    CheckUnaryOp({0x00}, OP_INVERT, {0xFF});
+    CheckUnaryOp({0xFF}, OP_INVERT, {0x00});
+    CheckUnaryOp({0xFF, 0xA0, 0xCE, 0xA0, 0x96, 0x12}, OP_INVERT,
+                 {0x00, 0x5F, 0x31, 0x5F, 0x69, 0xED});
+}
+
 /**
  * String opcodes.
  */