diff --git a/src/cmd/compile/internal/ssa/gen/RISCV64.rules b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
index 1ffb9575e0..316e5f3726 100644
--- a/src/cmd/compile/internal/ssa/gen/RISCV64.rules
+++ b/src/cmd/compile/internal/ssa/gen/RISCV64.rules
@@ -141,8 +141,7 @@
 // For positive x, bit 63 of x-1 is always 0, so the result is -1.
 // For zero x, bit 63 of x-1 is 1, so the result is 0.
 //
-// TODO(prattmic): Use XORconst etc instead of XOR (MOVDconst).
-(Slicemask <t> x) -> (XOR (MOVDconst [-1]) (SRA <t> (SUB <t> x (MOVDconst [1])) (MOVDconst [63])))
+(Slicemask <t> x) -> (XORI [-1] (SRAI <t> [63] (ADDI <t> [-1] x)))
 
 // Truncations
 // We ignore the unused high parts of registers, so truncates are just copies.
diff --git a/src/cmd/compile/internal/ssa/rewriteRISCV64.go b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
index 61da7a41bd..3b8d42b035 100644
--- a/src/cmd/compile/internal/ssa/rewriteRISCV64.go
+++ b/src/cmd/compile/internal/ssa/rewriteRISCV64.go
@@ -4230,27 +4230,20 @@ func rewriteValueRISCV64_OpSignExt8to64(v *Value) bool {
 func rewriteValueRISCV64_OpSlicemask(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
-	typ := &b.Func.Config.Types
 	// match: (Slicemask <t> x)
-	// result: (XOR (MOVDconst [-1]) (SRA <t> (SUB <t> x (MOVDconst [1])) (MOVDconst [63])))
+	// result: (XORI [-1] (SRAI <t> [63] (ADDI <t> [-1] x)))
 	for {
 		t := v.Type
 		x := v_0
-		v.reset(OpRISCV64XOR)
-		v0 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
-		v0.AuxInt = -1
+		v.reset(OpRISCV64XORI)
+		v.AuxInt = -1
+		v0 := b.NewValue0(v.Pos, OpRISCV64SRAI, t)
+		v0.AuxInt = 63
+		v1 := b.NewValue0(v.Pos, OpRISCV64ADDI, t)
+		v1.AuxInt = -1
+		v1.AddArg(x)
+		v0.AddArg(v1)
 		v.AddArg(v0)
-		v1 := b.NewValue0(v.Pos, OpRISCV64SRA, t)
-		v2 := b.NewValue0(v.Pos, OpRISCV64SUB, t)
-		v2.AddArg(x)
-		v3 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
-		v3.AuxInt = 1
-		v2.AddArg(v3)
-		v1.AddArg(v2)
-		v4 := b.NewValue0(v.Pos, OpRISCV64MOVDconst, typ.UInt64)
-		v4.AuxInt = 63
-		v1.AddArg(v4)
-		v.AddArg(v1)
 		return true
 	}
 }