diff --git a/main-command/src/main/scala/sbt/BasicCommands.scala b/main-command/src/main/scala/sbt/BasicCommands.scala
index 6ea7a6f9c..b78e147bb 100644
--- a/main-command/src/main/scala/sbt/BasicCommands.scala
+++ b/main-command/src/main/scala/sbt/BasicCommands.scala
@@ -208,10 +208,11 @@ object BasicCommands {
       else Parser.success(result.toList)
     }
 
-    (cmdParser ~ multiCmdParser.+).flatMap {
-      case ("", rest) => validateCommands(rest)
-      case (p, rest)  => validateCommands(rest).map(p :: _)
-    }
+    (cmdParser ~ multiCmdParser.+)
+      .flatMap {
+        case ("", rest) => validateCommands(rest)
+        case (p, rest)  => validateCommands(rest).map(p :: _)
+      }
   }
 
   def multiParser(s: State): Parser[List[String]] = multiParserImpl(Some(s))
diff --git a/main-command/src/main/scala/sbt/Command.scala b/main-command/src/main/scala/sbt/Command.scala
index 2244660a4..ec224b551 100644
--- a/main-command/src/main/scala/sbt/Command.scala
+++ b/main-command/src/main/scala/sbt/Command.scala
@@ -184,7 +184,8 @@ object Command {
     )
 
   def process(command: String, state: State): State = {
-    parse(command, state.combinedParser) match {
+    (if (command.contains(";")) parse(command, state.combinedParser)
+    else parse(command, state.nonMultiParser)) match {
       case Right(s) => s() // apply command.  command side effects happen here
       case Left(errMsg) =>
         state.log error errMsg
diff --git a/main-command/src/main/scala/sbt/State.scala b/main-command/src/main/scala/sbt/State.scala
index 32fd3c7a8..1d044cb3c 100644
--- a/main-command/src/main/scala/sbt/State.scala
+++ b/main-command/src/main/scala/sbt/State.scala
@@ -53,7 +53,11 @@ final case class State(
   private[sbt] lazy val (multiCommands, nonMultiCommands) =
     definedCommands.partition(_.nameOption.contains(BasicCommandStrings.Multi))
   private[sbt] lazy val nonMultiParser = Command.combine(nonMultiCommands)(this)
-  lazy val combinedParser = multiCommands.foldRight(nonMultiParser)(_.parser(this) | _)
+  lazy val combinedParser: Parser[() => State] =
+    multiCommands.headOption match {
+      case Some(multi) => multi.parser(this) | nonMultiParser
+      case _           => nonMultiParser
+    }
 
   def source: Option[CommandSource] =
     currentCommand match {
diff --git a/main-command/src/test/scala/sbt/MultiParserSpec.scala b/main-command/src/test/scala/sbt/MultiParserSpec.scala
index a2f580f10..88aea432d 100644
--- a/main-command/src/test/scala/sbt/MultiParserSpec.scala
+++ b/main-command/src/test/scala/sbt/MultiParserSpec.scala
@@ -14,7 +14,10 @@ import sbt.internal.util.complete.Parser
 object MultiParserSpec {
   val parser: Parser[Seq[String]] = BasicCommands.multiParserImpl(None)
   implicit class StringOps(val s: String) {
-    def parse: Seq[String] = Parser.parse(s, parser).right.get
+    def parse: Seq[String] = Parser.parse(s, parser) match {
+      case Right(x) => x
+      case Left(x)  => sys.error(s)
+    }
     def parseEither: Either[String, Seq[String]] = Parser.parse(s, parser)
   }
 }