diff --git a/src/cmd/go/internal/mvs/mvs.go b/src/cmd/go/internal/mvs/mvs.go
index d25d447b0e..a1b51557a3 100644
--- a/src/cmd/go/internal/mvs/mvs.go
+++ b/src/cmd/go/internal/mvs/mvs.go
@@ -194,6 +194,11 @@ func Req(mainModule module.Version, base []string, reqs Reqs) ([]module.Version,
 	// that list came from a previous operation that paged
 	// in all the requirements, so there's no I/O to overlap now.
 
+	max := map[string]string{}
+	for _, m := range list {
+		max[m.Path] = m.Version
+	}
+
 	// Compute postorder, cache requirements.
 	var postorder []module.Version
 	reqCache := map[module.Version][]module.Version{}
@@ -236,14 +241,6 @@ func Req(mainModule module.Version, base []string, reqs Reqs) ([]module.Version,
 		}
 		return nil
 	}
-	max := map[string]string{}
-	for _, m := range list {
-		if v, ok := max[m.Path]; ok {
-			max[m.Path] = reqs.Max(m.Version, v)
-		} else {
-			max[m.Path] = m.Version
-		}
-	}
 	// First walk the base modules that must be listed.
 	var min []module.Version
 	haveBase := map[string]bool{}