diff --git a/pkg/backup.go b/pkg/backup.go
index e5825e64f..42c8bf437 100644
--- a/pkg/backup.go
+++ b/pkg/backup.go
@@ -422,13 +422,7 @@ func (opt *mongoOptions) backupMongoDB(targetRef api_v1beta1.TargetRef) (*restic
 				fmt.Sprintf("--sslPEMKeyFile=%s", getOptionValue(dumpCreds, "--sslPEMKeyFile")))
 		}
 
-		var userArgs []string
-		for _, arg := range strings.Fields(opt.mongoArgs) {
-			// illegal argument combination: cannot specify --db and --uri
-			if !strings.Contains(arg, "--db") {
-				userArgs = append(userArgs, arg)
-			}
-		}
+		userArgs := strings.Fields(opt.mongoArgs)
 
 		if !isStandalone {
 			// - port is already added in mongoDSN with replicasetName/host:port format.
@@ -447,7 +441,10 @@ func (opt *mongoOptions) backupMongoDB(targetRef api_v1beta1.TargetRef) (*restic
 		}
 
 		for _, arg := range userArgs {
-			backupCmd.Args = append(backupCmd.Args, arg)
+			// illegal argument combination: cannot specify --db and --uri
+			if !strings.Contains(arg, "--db") {
+				backupCmd.Args = append(backupCmd.Args, arg)
+			}
 		}
 
 		// append the backup command into the pipe
diff --git a/pkg/restore.go b/pkg/restore.go
index 046a844b9..84ba0a98e 100644
--- a/pkg/restore.go
+++ b/pkg/restore.go
@@ -349,13 +349,7 @@ func (opt *mongoOptions) restoreMongoDB(targetRef api_v1beta1.TargetRef) (*resti
 				fmt.Sprintf("--sslPEMKeyFile=%s", getOptionValue(dumpCreds, "--sslPEMKeyFile")))
 		}
 
-		var userArgs []string
-		for _, arg := range strings.Fields(opt.mongoArgs) {
-			// illegal argument combination: cannot specify --db and --uri
-			if !strings.Contains(arg, "--db") {
-				userArgs = append(userArgs, arg)
-			}
-		}
+		userArgs := strings.Fields(opt.mongoArgs)
 
 		if !isStandalone {
 			// - port is already added in mongoDSN with replicasetName/host:port format.
@@ -378,7 +372,10 @@ func (opt *mongoOptions) restoreMongoDB(targetRef api_v1beta1.TargetRef) (*resti
 		}
 
 		for _, arg := range userArgs {
-			restoreCmd.Args = append(restoreCmd.Args, arg)
+			// illegal argument combination: cannot specify --db and --uri
+			if !strings.Contains(arg, "--db") {
+				restoreCmd.Args = append(restoreCmd.Args, arg)
+			}
 		}
 
 		// add the restore command to the pipeline
diff --git a/pkg/utils.go b/pkg/utils.go
index 0f6874f0a..b7c070cc6 100644
--- a/pkg/utils.go
+++ b/pkg/utils.go
@@ -159,21 +159,23 @@ func (opt *mongoOptions) buildMongoURI(mongoDSN string, port int32, isStandalone
 // remove "shard0/" prefix from shard0/simple-shard0-0.simple-shard0-pods.demo.svc:27017,simple-shard0-1.simple-shard0-pods.demo.svc:27017
 func extractHost(host string) string {
 	index := strings.Index(host, "/")
-	if index != -1 {
+	if index != -1 && index+1 < len(host) {
 		host = host[index+1:]
 	}
+	if index+1 >= len(host) {
+		host = ""
+	}
 	return host
 }
 
 func getBackupDB(mongoArgs string) string {
-	backupdb := "" // full
-	if strings.Contains(mongoArgs, "--db") {
+	if strings.Contains(mongoArgs, "--db=") {
 		args := strings.Fields(mongoArgs)
 		for _, arg := range args {
-			if strings.Contains(arg, "--db") {
-				backupdb = strings.Split(arg, "=")[1]
+			if strings.HasPrefix(arg, "--db=") {
+				return strings.TrimPrefix(arg, "--db=")
 			}
 		}
 	}
-	return backupdb
+	return ""
 }