diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
index 82c8302be..d8b5eccdb 100644
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -485,6 +485,12 @@ bool EvalScript(vector<vector<unsigned char> >& stack, const CScript& script, un
                         if (stack.size() < 1)
                             return set_error(serror, SCRIPT_ERR_UNBALANCED_CONDITIONAL);
                         valtype& vch = stacktop(-1);
+                        if (flags & SCRIPT_VERIFY_MINIMALIF) {
+                            if (vch.size() > 1)
+                                return set_error(serror, SCRIPT_ERR_MINIMALIF);
+                            if (vch.size() == 1 && vch[0] != 1)
+                                return set_error(serror, SCRIPT_ERR_MINIMALIF);
+                        }
                         fValue = CastToBool(vch);
                         if (opcode == OP_NOTIF)
                             fValue = !fValue;
diff --git a/src/script/interpreter.h b/src/script/interpreter.h
index 79a7b093e..55d1fc3ef 100644
--- a/src/script/interpreter.h
+++ b/src/script/interpreter.h
@@ -82,15 +82,19 @@ enum
     // See BIP65 for details.
     SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY = (1U << 9),
 
-	// Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
-	// (softfork safe)
-	SCRIPT_VERIFY_DERKEY = (1U << 10),
+    // Evaluating a pubkey that is not (0x04 + 64 bytes) or (0x02 or 0x03 + 32 bytes) by checksig causes script failure.
+    // (softfork safe)
+    SCRIPT_VERIFY_DERKEY = (1U << 10),
 
     // support CHECKSEQUENCEVERIFY opcode
     //
     // See BIP112 for details
     SCRIPT_VERIFY_CHECKSEQUENCEVERIFY = (1U << 10),
 
+    // Require the argument of OP_IF/NOTIF to be exactly 0x01 or empty vector
+    //
+    SCRIPT_VERIFY_MINIMALIF = (1U << 13),
+
     // Signature(s) must be empty vector if an CHECK(MULTI)SIG operation failed
     //
     SCRIPT_VERIFY_NULLFAIL = (1U << 14),
diff --git a/src/script/script_error.cpp b/src/script/script_error.cpp
index c06bce023..9ae757527 100644
--- a/src/script/script_error.cpp
+++ b/src/script/script_error.cpp
@@ -63,6 +63,8 @@ const char* ScriptErrorString(const ScriptError serror)
             return "Non-canonical signature: S value is unnecessarily high";
         case SCRIPT_ERR_SIG_NULLDUMMY:
             return "Dummy CHECKMULTISIG argument must be zero";
+        case SCRIPT_ERR_MINIMALIF:
+            return "OP_IF/NOTIF argument must be minimal";
         case SCRIPT_ERR_SIG_NULLFAIL:
             return "Signature must be zero for failed CHECK(MULTI)SIG operation";
         case SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS:
diff --git a/src/script/script_error.h b/src/script/script_error.h
index c3a31cb33..342b481dc 100644
--- a/src/script/script_error.h
+++ b/src/script/script_error.h
@@ -39,7 +39,7 @@ typedef enum ScriptError_t
     SCRIPT_ERR_NEGATIVE_LOCKTIME,
     SCRIPT_ERR_UNSATISFIED_LOCKTIME,
 
-    /* BIP62 */
+    /* Malleability */
     SCRIPT_ERR_SIG_HASHTYPE,
     SCRIPT_ERR_SIG_DER,
     SCRIPT_ERR_MINIMALDATA,
@@ -48,13 +48,14 @@ typedef enum ScriptError_t
     SCRIPT_ERR_SIG_NULLDUMMY,
     SCRIPT_ERR_PUBKEYTYPE,
     SCRIPT_ERR_CLEANSTACK,
+    SCRIPT_ERR_MINIMALIF,
     SCRIPT_ERR_SIG_NULLFAIL,
 
     /* softfork safeness */
     SCRIPT_ERR_DISCOURAGE_UPGRADABLE_NOPS,
-	
-	/* count acks */
-	SCRIPT_ERR_COUNT_ACKS_INVALID_PARAM,
+
+    /* count acks */
+    SCRIPT_ERR_COUNT_ACKS_INVALID_PARAM,
 
     SCRIPT_ERR_ERROR_COUNT
 } ScriptError;
diff --git a/src/test/transaction_tests.cpp b/src/test/transaction_tests.cpp
index d9195bf34..57704e5da 100644
--- a/src/test/transaction_tests.cpp
+++ b/src/test/transaction_tests.cpp
@@ -44,6 +44,7 @@ static std::map<string, unsigned int> mapFlagNames = boost::assign::map_list_of
     (string("NULLDUMMY"), (unsigned int)SCRIPT_VERIFY_NULLDUMMY)
     (string("DISCOURAGE_UPGRADABLE_NOPS"), (unsigned int)SCRIPT_VERIFY_DISCOURAGE_UPGRADABLE_NOPS)
     (string("CLEANSTACK"), (unsigned int)SCRIPT_VERIFY_CLEANSTACK)
+    (string("MINIMALIF"), (unsigned int)SCRIPT_VERIFY_MINIMALIF)
     (string("CHECKLOCKTIMEVERIFY"), (unsigned int)SCRIPT_VERIFY_CHECKLOCKTIMEVERIFY)
     (string("CHECKSEQUENCEVERIFY"), (unsigned int)SCRIPT_VERIFY_CHECKSEQUENCEVERIFY);