diff --git a/src/refit/application/rezk/REZKTestClientExists.java b/src/refit/application/rezk/REZKTestClientExists.java
index c2d6bb9f49b2f4ca0177484858cb20fb53d0bdd9..057930ead1677688641dfd23e46b08d96b984d53 100644
--- a/src/refit/application/rezk/REZKTestClientExists.java
+++ b/src/refit/application/rezk/REZKTestClientExists.java
@@ -9,18 +9,21 @@ import refit.util.REFITTime;
 public class REZKTestClientExists extends REZKTestClient {
 	private static final String[] prePaths = new String[2 * REFITConfig.NR_OF_NODES];
 
-	static {
-		for (int i = 0; i < prePaths.length; i++) {
-			prePaths[i] = String.format("%s%05d", "/node", i);
-		}
-	}
-
 	private String[] paths;
 	private boolean[] isValidPath;
 	private int counter = 0;
 
 	public REZKTestClientExists(REFITClientLibrary service) {
 		super(service);
+
+		synchronized (prePaths) {
+			if (prePaths[0] == null) {
+				for (int i = 0; i < prePaths.length; i++) {
+					prePaths[i] = String.format("%s%05d", "/node", i);
+				}
+			}
+		}
+
 		paths = new String[REFITConfig.NR_OF_NODES];
 		isValidPath = new boolean[paths.length];
 		// ensure reproducibility
diff --git a/src/refit/application/rezk/REZKTestClientReadWrite.java b/src/refit/application/rezk/REZKTestClientReadWrite.java
index a3d21b21ab978d23ed33cc4b3f279ad3c8deb46a..f45349a4c38459ffd27ec72e75a0347d7835ca3e 100644
--- a/src/refit/application/rezk/REZKTestClientReadWrite.java
+++ b/src/refit/application/rezk/REZKTestClientReadWrite.java
@@ -12,17 +12,20 @@ import refit.util.REFITTime;
 public class REZKTestClientReadWrite extends REZKTestClient {
 	private static final String[] paths = new String[REFITConfig.NR_OF_NODES];
 
-	static {
-		for (int i = 0; i < paths.length; i++) {
-			paths[i] = String.format("%s%05d", "/node", i);
-		}
-	}
-
 	private int counter = 0;
 	private Random rand;
 
 	public REZKTestClientReadWrite(REFITClientLibrary service) {
 		super(service);
+
+		synchronized (paths) {
+			if (paths[0] == null) {
+				for (int i = 0; i < paths.length; i++) {
+					paths[i] = String.format("%s%05d", "/node", i);
+				}
+			}
+		}
+
 		rand = new Random(service.getNodeID());
 	}
 
diff --git a/src/refit/application/rezk/REZKTestClientReadWriteActive.java b/src/refit/application/rezk/REZKTestClientReadWriteActive.java
index e45828eab14fe830179a4170c8c96a189e0eb635..7baf684bc5a6b106a18405bc57e0e19d7a5adaf9 100644
--- a/src/refit/application/rezk/REZKTestClientReadWriteActive.java
+++ b/src/refit/application/rezk/REZKTestClientReadWriteActive.java
@@ -11,18 +11,21 @@ import refit.util.REFITTime;
 public class REZKTestClientReadWriteActive extends REZKTestClient {
 	private static final String[] paths = new String[REFITConfig.NR_OF_NODES];
 
-	static {
-		for (int i = 0; i < paths.length; i++) {
-			paths[i] = String.format("%s%05d", "/node", i);
-		}
-	}
-
 	private static AtomicLong nextObj = new AtomicLong();
 	private int counter = 0;
 	private Random rand;
 
 	public REZKTestClientReadWriteActive(REFITClientLibrary service) {
 		super(service);
+
+		synchronized (paths) {
+			if (paths[0] == null) {
+				for (int i = 0; i < paths.length; i++) {
+					paths[i] = String.format("%s%05d", "/node", i);
+				}
+			}
+		}
+
 		rand = new Random(service.getNodeID());
 	}
 
diff --git a/src/refit/application/rezk/REZKTestClientReadWriteConflict.java b/src/refit/application/rezk/REZKTestClientReadWriteConflict.java
index bbab85b14cc21b2884f09d45dfe0081b098c39f5..1391f17055b9ab7fc21739f7f73e9894e28ae257 100644
--- a/src/refit/application/rezk/REZKTestClientReadWriteConflict.java
+++ b/src/refit/application/rezk/REZKTestClientReadWriteConflict.java
@@ -10,16 +10,19 @@ import refit.util.REFITTime;
 public class REZKTestClientReadWriteConflict extends REZKTestClient {
 	private static final String[] paths = new String[REFITConfig.ACTIVE_NODES];
 
-	static {
-		for (int i = 0; i < paths.length; i++) {
-			paths[i] = String.format("%s%05d", "/node", i);
-		}
-	}
-
 	private Random rand;
 
 	public REZKTestClientReadWriteConflict(REFITClientLibrary service) {
 		super(service);
+
+		synchronized (paths) {
+			if (paths[0] == null) {
+				for (int i = 0; i < paths.length; i++) {
+					paths[i] = String.format("%s%05d", "/node", i);
+				}
+			}
+		}
+
 		rand = new Random(service.getNodeID());
 	}