src/cmd/compile/internal/ssa/poset.go      |  3 +--
 src/cmd/compile/internal/ssa/poset_test.go |  4 ++--
 test/prove.go                              | 22 ++++++++++++++++++++++

diff --git a/src/cmd/compile/internal/ssa/poset.go b/src/cmd/compile/internal/ssa/poset.go
index 071297f8fa2baee138b4c29124ce6b0ab8f5c6e7..cf966c924c5c28b06c0a2d45e607338510caad62 100644
--- a/src/cmd/compile/internal/ssa/poset.go
+++ b/src/cmd/compile/internal/ssa/poset.go
@@ -814,8 +814,7 @@ 	if !f1 || !f2 {
 		return false
 	}
 
-	return i1 == i2 || po.reaches(i1, i2, false) ||
-		(po.reaches(i2, i1, false) && !po.reaches(i2, i1, true))
+	return i1 == i2 || po.reaches(i1, i2, false)
 }
 
 // Equal reports whether n1==n2. It returns false either when it is
diff --git a/src/cmd/compile/internal/ssa/poset_test.go b/src/cmd/compile/internal/ssa/poset_test.go
index cb739d9a0cecd1a541f8256b4f94436a06d35812..92c818a601e6afbb2464614c76575b6855acc95f 100644
--- a/src/cmd/compile/internal/ssa/poset_test.go
+++ b/src/cmd/compile/internal/ssa/poset_test.go
@@ -186,7 +186,7 @@ 		{NonEqual_Fail, 4, 100},
 		{OrderedOrEqual, 4, 12},
 		{OrderedOrEqual_Fail, 12, 4},
 		{OrderedOrEqual, 4, 7},
-		{OrderedOrEqual, 7, 4},
+		{OrderedOrEqual_Fail, 7, 4},
 
 		// Dag #1: 1<4<=7<12
 		{Checkpoint, 0, 0},
@@ -450,7 +450,7 @@ 		{SetOrder, 30, 40},
 		{SetOrderOrEqual, 20, 100},
 		{SetOrder, 100, 110},
 		{OrderedOrEqual, 10, 30},
-		{OrderedOrEqual, 30, 10},
+		{OrderedOrEqual_Fail, 30, 10},
 		{Ordered_Fail, 10, 30},
 		{Ordered_Fail, 30, 10},
 		{Ordered, 10, 40},
diff --git a/test/prove.go b/test/prove.go
index 6e92b9eec21a7ece724f5dc7ff56931b13014703..f6dd9f0955b952066c4704c1c2472de7c5e0a70d 100644
--- a/test/prove.go
+++ b/test/prove.go
@@ -853,6 +853,28 @@ 	}
 	return x
 }
 
+// Ensure that bounds checks with negative indexes are not incorrectly removed.
+func negIndex() {
+	n := make([]int, 1)
+	for i := -1; i <= 0; i++ { // ERROR "Induction variable: limits \[-1,0\], increment 1$"
+		n[i] = 1
+	}
+}
+func negIndex2(n int) {
+	a := make([]int, 5)
+	b := make([]int, 5)
+	c := make([]int, 5)
+	for i := -1; i <= 0; i-- {
+		b[i] = i
+		n++
+		if n > 10 {
+			break
+		}
+	}
+	useSlice(a)
+	useSlice(c)
+}
+
 //go:noinline
 func useInt(a int) {
 }