diff --git a/lib/Service/NegativeSampleGenerator.php b/lib/Service/NegativeSampleGenerator.php
index 99a3eecf..3705fc37 100644
--- a/lib/Service/NegativeSampleGenerator.php
+++ b/lib/Service/NegativeSampleGenerator.php
@@ -71,7 +71,7 @@ private function getUniqueIPsPerUser(Dataset $positives): array {
 	private function generateFromRealData(array $uidVec, array $uniqueIps): array {
 		return array_merge(
 			$uidVec,
-			$uniqueIps[random_int(0, count($uniqueIps) - 1)]
+			empty($uniqueIps) ? [] : $uniqueIps[random_int(0, count($uniqueIps) - 1)]
 		);
 	}
 
diff --git a/tests/Unit/Service/NegativeSampleGeneratorTest.php b/tests/Unit/Service/NegativeSampleGeneratorTest.php
index c04073e5..76fa1d3e 100644
--- a/tests/Unit/Service/NegativeSampleGeneratorTest.php
+++ b/tests/Unit/Service/NegativeSampleGeneratorTest.php
@@ -131,6 +131,17 @@ public function testGenerateMultipleShuffledFromLimitedUnique(): void {
 				'sample has a unique IP'
 			);
 		}
+
+		$positives = new Unlabeled([
+			array_merge(self::decToBitArray(1, 16), self::decToBitArray(1, 32)),
+			array_merge(self::decToBitArray(2, 16), self::decToBitArray(1, 32)),
+			array_merge(self::decToBitArray(3, 16), self::decToBitArray(1, 32)),
+			array_merge(self::decToBitArray(4, 16), self::decToBitArray(1, 32)),
+		]);
+
+		$result = $this->generator->generateShuffledFromPositiveSamples($positives, 5);
+
+		self::assertCount(5, $result);
 	}
 
 	/**