diff --git a/src/cmd/compile/internal/ssa/prove.go b/src/cmd/compile/internal/ssa/prove.go
index 1aab7e3eb77..39080a015e9 100644
--- a/src/cmd/compile/internal/ssa/prove.go
+++ b/src/cmd/compile/internal/ssa/prove.go
@@ -2885,9 +2885,9 @@ func simplifyBlock(sdom SparseTree, ft *factsTable, b *Block) {
 			xl := ft.limits[x.ID]
 			y := v.Args[1]
 			yl := ft.limits[y.ID]
-			if xl.umin == xl.umax && isPowerOfTwo(int64(xl.umin)) ||
+			if xl.umin == xl.umax && isUnsignedPowerOfTwo(xl.umin) ||
 				xl.min == xl.max && isPowerOfTwo(xl.min) ||
-				yl.umin == yl.umax && isPowerOfTwo(int64(yl.umin)) ||
+				yl.umin == yl.umax && isUnsignedPowerOfTwo(yl.umin) ||
 				yl.min == yl.max && isPowerOfTwo(yl.min) {
 				// 0,1 * a power of two is better done as a shift
 				break
diff --git a/test/prove.go b/test/prove.go
index 1b50317fe3e..e04b510e170 100644
--- a/test/prove.go
+++ b/test/prove.go
@@ -2718,6 +2718,14 @@ func detectStringLenRelation(s string) bool {
 	return false
 }
 
+func issue76688(x, y uint64) uint64 {
+	if x > 1 || y != 1<<63 {
+		return 42
+	}
+	// We do not want to rewrite the multiply to a condselect here since opt can do a better job with a left shift.
+	return x * y
+}
+
 //go:noinline
 func prove(x int) {
 }