diff --git a/src/cmd/compile/internal/ssa/_gen/generic.rules b/src/cmd/compile/internal/ssa/_gen/generic.rules
index b98dfae2d58..72d9677c5f2 100644
--- a/src/cmd/compile/internal/ssa/_gen/generic.rules
+++ b/src/cmd/compile/internal/ssa/_gen/generic.rules
@@ -297,6 +297,7 @@
 
 (CondSelect x _ (ConstBool [true ])) => x
 (CondSelect _ y (ConstBool [false])) => y
+(CondSelect x x _) => x
 
 // signed integer range: ( c <= x && x (<|<=) d ) -> ( unsigned(x-c) (<|<=) unsigned(d-c) )
 (AndB (Leq64 (Const64 [c]) x) ((Less|Leq)64 x (Const64 [d]))) && d >= c => ((Less|Leq)64U (Sub64 <x.Type> x (Const64 <x.Type> [c])) (Const64 <x.Type> [d-c]))
diff --git a/src/cmd/compile/internal/ssa/rewritegeneric.go b/src/cmd/compile/internal/ssa/rewritegeneric.go
index 0b9f9c09f9e..bdde103a1f3 100644
--- a/src/cmd/compile/internal/ssa/rewritegeneric.go
+++ b/src/cmd/compile/internal/ssa/rewritegeneric.go
@@ -5722,6 +5722,16 @@ func rewriteValuegeneric_OpCondSelect(v *Value) bool {
 		v.copyOf(y)
 		return true
 	}
+	// match: (CondSelect x x _)
+	// result: x
+	for {
+		x := v_0
+		if x != v_1 {
+			break
+		}
+		v.copyOf(x)
+		return true
+	}
 	// match: (CondSelect (Add8 <t> x (Const8 [1])) x bool)
 	// cond: config.arch != "arm64"
 	// result: (Add8 x (CvtBoolToUint8 <t> bool))