diff --git a/interpreter/binary/decode.ml b/interpreter/binary/decode.ml
index e1764be68..8238a93c3 100644
--- a/interpreter/binary/decode.ml
+++ b/interpreter/binary/decode.ml
@@ -395,6 +395,7 @@ let simd_prefix s =
   | 0xbfl -> i32x4_extmul_high_i16x8_u
   | 0xc0l -> i64x2_eq
   | 0xc1l -> i64x2_neg
+  | 0xc4l -> i64x2_bitmask
   | 0xcbl -> i64x2_shl
   | 0xccl -> i64x2_shr_s
   | 0xcdl -> i64x2_shr_u
diff --git a/interpreter/binary/encode.ml b/interpreter/binary/encode.ml
index 662b0bd5a..3fee6eaae 100644
--- a/interpreter/binary/encode.ml
+++ b/interpreter/binary/encode.ml
@@ -622,6 +622,7 @@ let encode m =
       | SimdBitmask Simd.I8x16 -> simd_op 0x64l
       | SimdBitmask Simd.I16x8 -> simd_op 0x84l
       | SimdBitmask Simd.I32x4 -> simd_op 0xa4l
+      | SimdBitmask Simd.I64x2 -> simd_op 0xc4l
       | SimdBitmask (_) -> assert false
 
       | _ -> assert false
diff --git a/interpreter/exec/eval_simd.ml b/interpreter/exec/eval_simd.ml
index 6ab68766f..a5745af75 100644
--- a/interpreter/exec/eval_simd.ml
+++ b/interpreter/exec/eval_simd.ml
@@ -233,6 +233,7 @@ module SimdOp (SXX : Simd.S) (Value : ValueType with type t = SXX.t) = struct
     | Simd.I8x16 -> SXX.I8x16.bitmask
     | Simd.I16x8 -> SXX.I16x8.bitmask
     | Simd.I32x4 -> SXX.I32x4.bitmask
+    | Simd.I64x2 -> SXX.I64x2.bitmask
     | _ -> assert false
     in I32 (f (of_value 1 v))
 
diff --git a/interpreter/syntax/operators.ml b/interpreter/syntax/operators.ml
index 936c0f791..7ad59a8d3 100644
--- a/interpreter/syntax/operators.ml
+++ b/interpreter/syntax/operators.ml
@@ -390,6 +390,7 @@ let i64x2_replace_lane imm = SimdReplace (V128Op.I64x2 imm)
 let i64x2_eq = Binary (V128 V128Op.(I64x2 Eq))
 let i64x2_ne = Binary (V128 V128Op.(I64x2 Ne))
 let i64x2_neg = Unary (V128 V128Op.(I64x2 Neg))
+let i64x2_bitmask = SimdBitmask Simd.I64x2
 let i64x2_add = Binary (V128 V128Op.(I64x2 Add))
 let i64x2_sub = Binary (V128 V128Op.(I64x2 Sub))
 let i64x2_mul = Binary (V128 V128Op.(I64x2 Mul))
diff --git a/interpreter/text/arrange.ml b/interpreter/text/arrange.ml
index cb53033c7..c20515a1e 100644
--- a/interpreter/text/arrange.ml
+++ b/interpreter/text/arrange.ml
@@ -406,6 +406,7 @@ struct
     | Simd.I8x16 -> "i8x16.bitmask"
     | Simd.I16x8 -> "i16x8.bitmask"
     | Simd.I32x4 -> "i32x4.bitmask"
+    | Simd.I64x2 -> "i64x2.bitmask"
     | _ -> assert false
 
 end
diff --git a/interpreter/text/lexer.mll b/interpreter/text/lexer.mll
index 9058de503..04707f059 100644
--- a/interpreter/text/lexer.mll
+++ b/interpreter/text/lexer.mll
@@ -536,8 +536,7 @@ rule token = parse
     { only ["i8x16"; "i16x8"; "i32x4"] s lexbuf;
       UNARY (simd_int_op s i8x16_all_true i16x8_all_true i32x4_all_true unreachable) }
   | (simd_int_shape as s)".bitmask"
-    { only ["i8x16"; "i16x8"; "i32x4"] s lexbuf;
-      UNARY (simd_int_op s i8x16_bitmask i16x8_bitmask i32x4_bitmask unreachable) }
+    { UNARY (simd_int_op s i8x16_bitmask i16x8_bitmask i32x4_bitmask i64x2_bitmask) }
   | (simd_int_shape as s)".shl"
     { SHIFT (simd_int_op s i8x16_shl i16x8_shl i32x4_shl i64x2_shl) }
   | (simd_int_shape as s)".shr_s"
diff --git a/test/core/simd/simd_boolean.wast b/test/core/simd/simd_boolean.wast
index 3fee25207..8eb0c8719 100644
--- a/test/core/simd/simd_boolean.wast
+++ b/test/core/simd/simd_boolean.wast
@@ -12,6 +12,8 @@
   (func (export "i32x4.any_true") (param $0 v128) (result i32) (v128.any_true (local.get $0)))
   (func (export "i32x4.all_true") (param $0 v128) (result i32) (i32x4.all_true (local.get $0)))
   (func (export "i32x4.bitmask") (param $0 v128) (result i32) (i32x4.bitmask (local.get $0)))
+
+  (func (export "i64x2.bitmask") (param $0 v128) (result i32) (i64x2.bitmask (local.get $0)))
 )
 
 ;; i8x16
@@ -156,6 +158,11 @@
 (assert_return (invoke "i32x4.bitmask" (v128.const i32x4 -1 0 1 0xF))
                                         (i32.const 0x00000001))
 
+(assert_return (invoke "i64x2.bitmask" (v128.const i64x2 0xFFFFFFFF_FFFFFFFF 0xFFFFFFFF_FFFFFFFF))
+                                        (i32.const 0x00000003))
+(assert_return (invoke "i64x2.bitmask" (v128.const i64x2 -1 0xF))
+                                        (i32.const 0x00000001))
+
 ;; Combination
 
 (module (memory 1)