diff --git a/src/world/format/io/FormatConverter.php b/src/world/format/io/FormatConverter.php
index 1d485afa21..421d707fa6 100644
--- a/src/world/format/io/FormatConverter.php
+++ b/src/world/format/io/FormatConverter.php
@@ -33,6 +33,7 @@ use function basename;
 use function crc32;
 use function file_exists;
 use function floor;
+use function flush;
 use function microtime;
 use function mkdir;
 use function random_bytes;
@@ -150,6 +151,10 @@ class FormatConverter{
 				$diff = $time - $thisRound;
 				$thisRound = $time;
 				$this->logger->info("Converted $counter / $count chunks (" . floor($this->chunksPerProgressUpdate / $diff) . " chunks/sec)");
+				flush();
+			}
+			if(($counter % (2 ** 16)) === 0){
+				$new->doGarbageCollection();
 			}
 		}
 		$total = microtime(true) - $start;
diff --git a/tools/convert-world.php b/tools/convert-world.php
index d4d15ce57b..828ccb470d 100644
--- a/tools/convert-world.php
+++ b/tools/convert-world.php
@@ -52,7 +52,7 @@ $writableFormats = array_filter($providerManager->getAvailableProviders(), fn(Wo
 $requiredOpts = [
 	"world" => "path to the input world for conversion",
 	"backup" => "path to back up the original files",
-	"format" => "desired output format (can be one of: " . implode(",", array_keys($writableFormats)) . ")"
+	"format" => "desired output format (can be one of: " . implode(", ", array_keys($writableFormats)) . ")"
 ];
 $usageMessage = "Options:\n";
 foreach($requiredOpts as $_opt => $_desc){
@@ -89,7 +89,7 @@ if(count($oldProviderClasses) === 0){
 	exit(1);
 }
 if(count($oldProviderClasses) > 1){
-	fwrite(STDERR, "Ambiguous input world format: matched " . count($oldProviderClasses) . " (" . implode(array_keys($oldProviderClasses)) . ")" . PHP_EOL);
+	fwrite(STDERR, "Ambiguous input world format: matched " . count($oldProviderClasses) . " (" . implode(", ", array_keys($oldProviderClasses)) . ")" . PHP_EOL);
 	exit(1);
 }
 $oldProviderClass = array_shift($oldProviderClasses);