diff --git a/src/main/java/com/onthegomap/flatmap/reader/NaturalEarthReader.java b/src/main/java/com/onthegomap/flatmap/reader/NaturalEarthReader.java
index 3e47e938..c3c37803 100644
--- a/src/main/java/com/onthegomap/flatmap/reader/NaturalEarthReader.java
+++ b/src/main/java/com/onthegomap/flatmap/reader/NaturalEarthReader.java
@@ -6,10 +6,9 @@ import com.onthegomap.flatmap.monitoring.Stats;
 import com.onthegomap.flatmap.worker.Topology.SourceStep;
 import java.io.File;
 import java.io.IOException;
-import java.nio.file.FileSystem;
-import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardCopyOption;
 import java.sql.Connection;
 import java.sql.DriverManager;
 import java.sql.ResultSet;
@@ -17,7 +16,6 @@ import java.sql.SQLException;
 import java.sql.Statement;
 import java.util.ArrayList;
 import java.util.List;
-import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import org.locationtech.jts.geom.Geometry;
 import org.slf4j.Logger;
@@ -45,30 +43,17 @@ public class NaturalEarthReader extends Reader {
 
   private Connection open(File file, File tmpLocation) throws IOException, SQLException {
     String path = "jdbc:sqlite:" + file.getAbsolutePath();
-    File toOpen = file;
     if (file.getName().endsWith(".zip")) {
-      toOpen = tmpLocation == null ? File.createTempFile("sqlite", "natearth") : tmpLocation;
+      File toOpen = tmpLocation == null ? File.createTempFile("sqlite", "natearth") : tmpLocation;
       extracted = toOpen.toPath();
-      toOpen.delete();
       toOpen.deleteOnExit();
-      String sqliteFileInZip;
-      try (ZipFile zip = new ZipFile(file)) {
-        sqliteFileInZip = zip.stream()
-          .map(ZipEntry::getName)
-          .filter(z -> z.endsWith(".sqlite"))
-          .findFirst().orElse(null);
-      }
-      if (sqliteFileInZip == null) {
-        throw new IllegalArgumentException("No .sqlite file found inside " + file.getName());
-      } else {
+      try (ZipFile zipFile = new ZipFile(file)) {
+        var zipEntry = zipFile.stream()
+          .filter(entry -> entry.getName().endsWith(".sqlite"))
+          .findFirst()
+          .orElseThrow(() -> new IllegalArgumentException("No .sqlite file found inside " + file.getName()));
         LOGGER.info("unzipping " + file.getAbsolutePath() + " to " + extracted);
-        try (FileSystem fileSystem = FileSystems.newFileSystem(file.toPath())) {
-          Path fileToExtract = fileSystem.getPath(sqliteFileInZip);
-          Files.copy(
-            fileToExtract,
-            extracted
-          );
-        }
+        Files.copy(zipFile.getInputStream(zipEntry), extracted, StandardCopyOption.REPLACE_EXISTING);
       }
       path = "jdbc:sqlite:" + toOpen.getAbsolutePath();
     }
diff --git a/src/main/java/com/onthegomap/flatmap/reader/ShapefileReader.java b/src/main/java/com/onthegomap/flatmap/reader/ShapefileReader.java
index daec6c1d..ba846e3d 100644
--- a/src/main/java/com/onthegomap/flatmap/reader/ShapefileReader.java
+++ b/src/main/java/com/onthegomap/flatmap/reader/ShapefileReader.java
@@ -28,7 +28,7 @@ import org.opengis.referencing.operation.MathTransform;
 public class ShapefileReader extends Reader implements Closeable {
 
   private final FeatureCollection<SimpleFeatureType, SimpleFeature> inputSource;
-  private String[] attributeNames;
+  private final String[] attributeNames;
   private final ShapefileDataStore dataStore;
   private MathTransform transform;
 
@@ -76,17 +76,14 @@ public class ShapefileReader extends Reader implements Closeable {
       URI uri;
 
       if (name.endsWith(".zip")) {
-        String shapeFileInZip;
         try (ZipFile zip = new ZipFile(file)) {
-          shapeFileInZip = zip.stream()
+          String shapeFileInZip = zip.stream()
             .map(ZipEntry::getName)
             .filter(z -> z.endsWith(".shp"))
-            .findAny().orElse(null);
+            .findFirst()
+            .orElseThrow(() -> new IllegalArgumentException("No .shp file found inside " + name));
+          uri = URI.create("jar:file:" + file.toPath().toAbsolutePath() + "!/" + shapeFileInZip);
         }
-        if (shapeFileInZip == null) {
-          throw new IllegalArgumentException("No .shp file found inside " + name);
-        }
-        uri = URI.create("jar:file:" + file.toPath().toAbsolutePath() + "!/" + shapeFileInZip);
       } else if (name.endsWith(".shp")) {
         uri = file.toURI();
       } else {
diff --git a/src/main/java/com/onthegomap/flatmap/worker/Topology.java b/src/main/java/com/onthegomap/flatmap/worker/Topology.java
index 0c718e0f..9311a828 100644
--- a/src/main/java/com/onthegomap/flatmap/worker/Topology.java
+++ b/src/main/java/com/onthegomap/flatmap/worker/Topology.java
@@ -23,9 +23,9 @@ public record Topology<T>(
   private void doAwaitAndLog(ProgressLoggers loggers, Duration logInterval, long startNanos) {
     if (previous != null) {
       previous.doAwaitAndLog(loggers, logInterval, startNanos);
-    }
-    if (inputQueue != null) {
-      inputQueue.close();
+      if (inputQueue != null) {
+        inputQueue.close();
+      }
     }
     if (worker != null) {
       long elapsedSoFar = System.nanoTime() - startNanos;
@@ -43,9 +43,9 @@ public record Topology<T>(
   public void await() {
     if (previous != null) {
       previous.await();
-    }
-    if (inputQueue != null) {
-      inputQueue.close();
+      if (inputQueue != null) {
+        inputQueue.close();
+      }
     }
     if (worker != null) {
       worker.await();
diff --git a/src/test/java/com/onthegomap/flatmap/worker/TopologyTest.java b/src/test/java/com/onthegomap/flatmap/worker/TopologyTest.java
index d6c1f955..e826a9da 100644
--- a/src/test/java/com/onthegomap/flatmap/worker/TopologyTest.java
+++ b/src/test/java/com/onthegomap/flatmap/worker/TopologyTest.java
@@ -55,14 +55,15 @@ public class TopologyTest {
       }).addBuffer("writer_queue", 1)
       .sinkToConsumer("writer", 1, result::add);
 
-    queue.accept(0);
-    queue.accept(1);
-    queue.accept(2);
-    queue.close();
+    new Thread(() -> {
+      queue.accept(0);
+      queue.accept(1);
+      queue.close();
+    }).start();
 
     topology.await();
 
-    assertEquals(Set.of(1, 2, 3, 4, 5, 6), result);
+    assertEquals(Set.of(1, 2, 3, 4), result);
   }
 
   @Test