diff --git a/src/Stream.php b/src/Stream.php
index 4c17007..36da18c 100644
--- a/src/Stream.php
+++ b/src/Stream.php
@@ -7,12 +7,16 @@ class Stream {
 	const IN = "in";
 	const OUT = "out";
 	const ERROR = "error";
+	const REPEAT_CHAR = "⟲";
 
 	protected SplFileObject $error;
 	protected SplFileObject $out;
 	protected SplFileObject $in;
 	protected SplFileObject $currentStream;
 
+	protected string $lastLineBuffer;
+	private bool $lastLineRepeats;
+
 	public function __construct(
 		string $in = null,
 		string $out = null,
@@ -29,6 +33,8 @@ public function __construct(
 		}
 
 		$this->setStream($in, $out, $error);
+		$this->lastLineBuffer = "";
+		$this->lastLineRepeats = false;
 	}
 
 	public function setStream(string $in, string $out, string $error):void {
@@ -81,7 +87,22 @@ public function writeLine(
 		string $message = "",
 		string $streamName = self::OUT
 	):void {
-		$this->write($message . PHP_EOL, $streamName);
+		$message .= PHP_EOL;
+
+		if($message === $this->lastLineBuffer) {
+			$this->write(self::REPEAT_CHAR, $streamName);
+			$this->lastLineRepeats = true;
+		}
+		else {
+			if($this->lastLineRepeats) {
+				$this->write(PHP_EOL, $streamName);
+			}
+
+			$this->write($message, $streamName);
+			$this->lastLineRepeats = false;
+		}
+
+		$this->lastLineBuffer = $message;
 	}
 
 	protected function getNamedStream(string $streamName):SplFileObject {
diff --git a/test/phpunit/StreamTest.php b/test/phpunit/StreamTest.php
index 32e3657..177c1f6 100644
--- a/test/phpunit/StreamTest.php
+++ b/test/phpunit/StreamTest.php
@@ -117,4 +117,32 @@ public function testInvalidStreamName() {
 		$this->expectException(InvalidStreamNameException::class);
 		$stream->write("this does not exist", "nothing");
 	}
-}
\ No newline at end of file
+
+	public function testRepeatingLineSuppressed():void {
+		$stream = new Stream(
+			"php://memory",
+			"php://memory",
+			"php://memory",
+		);
+		$out = $stream->getOutStream();
+
+		for($i = 1; $i <= 10; $i++) {
+			$stream->writeLine("This is message $i, and should appear individually.");
+		}
+
+		for($i = 1; $i <= 5; $i++) {
+			$stream->writeLine("This message is sent 5 times but should only appear once.");
+		}
+
+		for($i = 11; $i <= 20; $i++) {
+			$stream->writeLine("This is message $i, and should appear after the repeating message individually.");
+		}
+
+		$out->rewind();
+		$fullStreamContents = $out->fread(1024);
+
+		self::assertSame(10, substr_count($fullStreamContents, "should appear individually"), "Unique messages should appear individually");
+		self::assertSame(1, substr_count($fullStreamContents, "should only appear once"), "Similar messages should only appear once");
+		self::assertSame(4, substr_count($fullStreamContents, Stream::REPEAT_CHAR));
+	}
+}