diff --git a/src/cmd/compile/internal/ssa/_gen/Wasm.rules b/src/cmd/compile/internal/ssa/_gen/Wasm.rules
index bf48ed4348..8490fb39b8 100644
--- a/src/cmd/compile/internal/ssa/_gen/Wasm.rules
+++ b/src/cmd/compile/internal/ssa/_gen/Wasm.rules
@@ -374,6 +374,7 @@
 
 // --- Optimizations ---
 (I64Add (I64Const [x]) (I64Const [y])) => (I64Const [x + y])
+(I64Sub (I64Const [x]) (I64Const [y])) => (I64Const [x - y])
 (I64Mul (I64Const [x]) (I64Const [y])) => (I64Const [x * y])
 (I64And (I64Const [x]) (I64Const [y])) => (I64Const [x & y])
 (I64Or  (I64Const [x]) (I64Const [y])) => (I64Const [x | y])
diff --git a/src/cmd/compile/internal/ssa/rewriteWasm.go b/src/cmd/compile/internal/ssa/rewriteWasm.go
index 94535bfbc7..68a40f0c7f 100644
--- a/src/cmd/compile/internal/ssa/rewriteWasm.go
+++ b/src/cmd/compile/internal/ssa/rewriteWasm.go
@@ -656,6 +656,8 @@ func rewriteValueWasm(v *Value) bool {
 		return rewriteValueWasm_OpWasmI64Store32(v)
 	case OpWasmI64Store8:
 		return rewriteValueWasm_OpWasmI64Store8(v)
+	case OpWasmI64Sub:
+		return rewriteValueWasm_OpWasmI64Sub(v)
 	case OpWasmI64Xor:
 		return rewriteValueWasm_OpWasmI64Xor(v)
 	case OpXor16:
@@ -4746,6 +4748,26 @@ func rewriteValueWasm_OpWasmI64Store8(v *Value) bool {
 	}
 	return false
 }
+func rewriteValueWasm_OpWasmI64Sub(v *Value) bool {
+	v_1 := v.Args[1]
+	v_0 := v.Args[0]
+	// match: (I64Sub (I64Const [x]) (I64Const [y]))
+	// result: (I64Const [x - y])
+	for {
+		if v_0.Op != OpWasmI64Const {
+			break
+		}
+		x := auxIntToInt64(v_0.AuxInt)
+		if v_1.Op != OpWasmI64Const {
+			break
+		}
+		y := auxIntToInt64(v_1.AuxInt)
+		v.reset(OpWasmI64Const)
+		v.AuxInt = int64ToAuxInt(x - y)
+		return true
+	}
+	return false
+}
 func rewriteValueWasm_OpWasmI64Xor(v *Value) bool {
 	v_1 := v.Args[1]
 	v_0 := v.Args[0]