diff --git a/pdb-api/src/test/java/org/lucares/pdb/api/StringCompressorTest.java b/pdb-api/src/test/java/org/lucares/pdb/api/StringCompressorTest.java
index e2b506c..5878a9c 100644
--- a/pdb-api/src/test/java/org/lucares/pdb/api/StringCompressorTest.java
+++ b/pdb-api/src/test/java/org/lucares/pdb/api/StringCompressorTest.java
@@ -3,10 +3,7 @@ package org.lucares.pdb.api;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import java.util.ArrayList;
 import java.util.List;
-import java.util.UUID;
-import java.util.concurrent.Callable;
 import java.util.concurrent.ExecutionException;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
@@ -59,29 +56,6 @@ public class StringCompressorTest {
 
 	}
 
-	private static final class StringInserter implements Callable<List<String>> {
-
-		private final StringCompressor stringCompressor;
-		private final int numEntries;
-
-		public StringInserter(final StringCompressor stringCompressor, final int numEntries) {
-			this.stringCompressor = stringCompressor;
-			this.numEntries = numEntries;
-		}
-
-		@Override
-		public List<String> call() throws Exception {
-
-			final List<String> result = new ArrayList<>();
-			for (int i = 0; i < numEntries; i++) {
-				final String s = UUID.randomUUID().toString();
-				stringCompressor.put(s);
-				result.add(s);
-			}
-			return result;
-		}
-	};
-
 	@Test(invocationCount = 1)
 	public void testPutConcurrently() throws InterruptedException, ExecutionException {
 		final UniqueStringIntegerPairs usip = new UniqueStringIntegerPairs();
diff --git a/pdb-api/src/test/java/org/lucares/pdb/api/StringInserter.java b/pdb-api/src/test/java/org/lucares/pdb/api/StringInserter.java
new file mode 100644
index 0000000..a98f725
--- /dev/null
+++ b/pdb-api/src/test/java/org/lucares/pdb/api/StringInserter.java
@@ -0,0 +1,29 @@
+package org.lucares.pdb.api;
+
+import java.util.ArrayList;
+import java.util.List;
+import java.util.UUID;
+import java.util.concurrent.Callable;
+
+final class StringInserter implements Callable<List<String>> {
+
+	private final StringCompressor stringCompressor;
+	private final int numEntries;
+
+	public StringInserter(final StringCompressor stringCompressor, final int numEntries) {
+		this.stringCompressor = stringCompressor;
+		this.numEntries = numEntries;
+	}
+
+	@Override
+	public List<String> call() throws Exception {
+
+		final List<String> result = new ArrayList<>();
+		for (int i = 0; i < numEntries; i++) {
+			final String s = UUID.randomUUID().toString();
+			stringCompressor.put(s);
+			result.add(s);
+		}
+		return result;
+	}
+}
\ No newline at end of file