diff --git a/libcontainer/configs/validate/rootless.go b/libcontainer/configs/validate/rootless.go
index 7afdb4310f9..99ab3f8f389 100644
--- a/libcontainer/configs/validate/rootless.go
+++ b/libcontainer/configs/validate/rootless.go
@@ -2,7 +2,7 @@ package validate
 
 import (
 	"errors"
-	"fmt"
+	"strconv"
 	"strings"
 
 	"github.com/opencontainers/runc/libcontainer/configs"
@@ -51,9 +51,8 @@ func rootlessEUIDMappings(config *configs.Config) error {
 	return nil
 }
 
-// mount verifies that the user isn't trying to set up any mounts they don't have
-// the rights to do. In addition, it makes sure that no mount has a `uid=` or
-// `gid=` option that doesn't resolve to root.
+// rootlessEUIDMount verifies that all mounts have valid uid=/gid= options,
+// i.e. their arguments has proper ID mappings.
 func rootlessEUIDMount(config *configs.Config) error {
 	// XXX: We could whitelist allowed devices at this point, but I'm not
 	//      convinced that's a good idea. The kernel is the best arbiter of
@@ -63,10 +62,9 @@ func rootlessEUIDMount(config *configs.Config) error {
 		// Check that the options list doesn't contain any uid= or gid= entries
 		// that don't resolve to root.
 		for _, opt := range strings.Split(mount.Data, ",") {
-			if strings.HasPrefix(opt, "uid=") {
-				var uid int
-				n, err := fmt.Sscanf(opt, "uid=%d", &uid)
-				if n != 1 || err != nil {
+			if str := strings.TrimPrefix(opt, "uid="); len(str) < len(opt) {
+				uid, err := strconv.Atoi(str)
+				if err != nil {
 					// Ignore unknown mount options.
 					continue
 				}
@@ -75,10 +73,9 @@ func rootlessEUIDMount(config *configs.Config) error {
 				}
 			}
 
-			if strings.HasPrefix(opt, "gid=") {
-				var gid int
-				n, err := fmt.Sscanf(opt, "gid=%d", &gid)
-				if n != 1 || err != nil {
+			if str := strings.TrimPrefix(opt, "gid="); len(str) < len(opt) {
+				gid, err := strconv.Atoi(str)
+				if err != nil {
 					// Ignore unknown mount options.
 					continue
 				}
diff --git a/libcontainer/configs/validate/rootless_test.go b/libcontainer/configs/validate/rootless_test.go
index 0657abf48dc..0e8df6eb297 100644
--- a/libcontainer/configs/validate/rootless_test.go
+++ b/libcontainer/configs/validate/rootless_test.go
@@ -141,3 +141,24 @@ func TestValidateRootlessEUIDMountGid(t *testing.T) {
 		t.Errorf("Expected error to occur when setting gid=11 in mount options and GidMapping[0].size is 10")
 	}
 }
+
+func BenchmarkRootlessEUIDMount(b *testing.B) {
+	config := rootlessEUIDConfig()
+	config.GidMappings[0].Size = 10
+	config.Mounts = []*configs.Mount{
+		{
+			Source:      "devpts",
+			Destination: "/dev/pts",
+			Device:      "devpts",
+			Data:        "newinstance,ptmxmode=0666,mode=0620,uid=0,gid=5",
+		},
+	}
+
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		err := rootlessEUIDMount(config)
+		if err != nil {
+			b.Fatal(err)
+		}
+	}
+}