diff --git a/src/script/interpreter.cpp b/src/script/interpreter.cpp
--- a/src/script/interpreter.cpp
+++ b/src/script/interpreter.cpp
@@ -913,11 +913,6 @@
 
                     case OP_CHECKDATASIG:
                     case OP_CHECKDATASIGVERIFY: {
-                        // Make sure this remains an error before activation.
-                        if ((flags & SCRIPT_ENABLE_CHECKDATASIG) == 0) {
-                            return set_error(serror, SCRIPT_ERR_BAD_OPCODE);
-                        }
-
                         // (sig message pubkey -- bool)
                         if (stack.size() < 3) {
                             return set_error(
diff --git a/src/script/script_flags.h b/src/script/script_flags.h
--- a/src/script/script_flags.h
+++ b/src/script/script_flags.h
@@ -95,8 +95,9 @@
     //
     SCRIPT_ENABLE_REPLAY_PROTECTION = (1U << 17),
 
-    // Is OP_CHECKDATASIG and variant are enabled, and must be counted towards
-    // Sigops limits.
+    // Count sigops for OP_CHECKDATASIG and variant. The interpreter treats
+    // OP_CHECKDATASIG(VERIFY) as always valid, this flag only affects sigops
+    // counting.
     //
     SCRIPT_ENABLE_CHECKDATASIG = (1U << 18),
 
diff --git a/src/test/checkdatasig_tests.cpp b/src/test/checkdatasig_tests.cpp
--- a/src/test/checkdatasig_tests.cpp
+++ b/src/test/checkdatasig_tests.cpp
@@ -66,12 +66,11 @@
                                        const CScript &script,
                                        const stacktype &expected) {
     for (uint32_t flags : flagset) {
-        // Make sure that we get a bad opcode when the activation flag is not
-        // passed.
-        CheckError(flags & ~SCRIPT_ENABLE_CHECKDATASIG, original_stack, script,
-                   SCRIPT_ERR_BAD_OPCODE);
+        // The script executes as expected if the opcodes are not activated.
+        CheckPass(flags & ~SCRIPT_ENABLE_CHECKDATASIG, original_stack, script,
+                  expected);
 
-        // The script execute as expected if the opcodes are activated.
+        // The script executes as expected if the opcodes are activated.
         CheckPass(flags | SCRIPT_ENABLE_CHECKDATASIG, original_stack, script,
                   expected);
     }
@@ -80,10 +79,10 @@
 static void CheckErrorForAllFlags(const stacktype &original_stack,
                                   const CScript &script, ScriptError expected) {
     for (uint32_t flags : flagset) {
-        // Make sure that we get a bad opcode when the activation flag is not
-        // passed.
+        // The script generates the proper error if the opcodes are not
+        // activated.
         CheckError(flags & ~SCRIPT_ENABLE_CHECKDATASIG, original_stack, script,
-                   SCRIPT_ERR_BAD_OPCODE);
+                   expected);
 
         // The script generates the proper error if the opcodes are activated.
         CheckError(flags | SCRIPT_ENABLE_CHECKDATASIG, original_stack, script,
diff --git a/src/test/data/script_tests.json b/src/test/data/script_tests.json
--- a/src/test/data/script_tests.json
+++ b/src/test/data/script_tests.json
@@ -1233,8 +1233,6 @@
  "P2SH,DISCOURAGE_UPGRADABLE_NOPS", "DISCOURAGE_UPGRADABLE_NOPS", "Discouraged NOP10 in redeemScript"],
 
 ["0x50","1", "P2SH,STRICTENC", "BAD_OPCODE", "opcode 0x50 is reserved"],
-["1", "IF CHECKDATASIG ELSE 1 ENDIF", "P2SH,STRICTENC", "BAD_OPCODE"],
-["1", "IF CHECKDATASIGVERIFY ELSE 1 ENDIF", "P2SH,STRICTENC", "BAD_OPCODE"],
 ["1", "IF 0xbc ELSE 1 ENDIF", "P2SH,STRICTENC", "BAD_OPCODE", "opcodes >= FIRST_UNDEFINED_OP_VALUE invalid if executed"],
 ["1", "IF 0xbd ELSE 1 ENDIF", "P2SH,STRICTENC", "BAD_OPCODE"],
 ["1", "IF 0xbe ELSE 1 ENDIF", "P2SH,STRICTENC", "BAD_OPCODE"],
@@ -2314,6 +2312,13 @@
     "Standard CHECKDATASIG"
 ],
 [
+    "0x46 0x3044022021309a532a60d471cc4ef025a96572c7bf26c4640b53c7d45e411a5aa99980f6022037964f01a61db1b24ea44137b3d67d7095ec25f68bd7b508e01441e5539d96a9 0",
+    "0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 CHECKDATASIG",
+    "NULLFAIL,STRICTENC",
+    "OK",
+    "Standard CHECKDATASIG without CHECKDATASIG flag"
+],
+[
     "0x46 0x3044022021309a532a60d471cc4ef025a96572c7bf26c4640b53c7d45e411a5aa99980f6022037964f01a61db1b24ea44137b3d67d7095ec25f68bd7b508e01441e5539d96a9 1",
     "0x21 0x038282263212c609d9ea2a6e3e172de238d8c39cabd5ac1ca10646e23fd5f51508 CHECKDATASIG NOT",
     "CHECKDATASIG,NULLFAIL,STRICTENC",