diff --git a/flo-runner/src/main/java/com/spotify/flo/context/ForkingExecutor.java b/flo-runner/src/main/java/com/spotify/flo/context/ForkingExecutor.java
index ac402426b..58c750f32 100644
--- a/flo-runner/src/main/java/com/spotify/flo/context/ForkingExecutor.java
+++ b/flo-runner/src/main/java/com/spotify/flo/context/ForkingExecutor.java
@@ -23,9 +23,9 @@
 import com.spotify.flo.Fn;
 import com.spotify.flo.Serialization;
 import com.spotify.flo.SerializationException;
-import com.spotify.flo.freezer.PersistingContext;
 import java.io.BufferedReader;
 import java.io.Closeable;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.InputStreamReader;
@@ -48,6 +48,7 @@
 import java.util.Objects;
 import java.util.concurrent.ExecutorService;
 import java.util.concurrent.Executors;
+import java.util.stream.Collectors;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -135,9 +136,14 @@ void start() {
       } catch (SerializationException e) {
         throw new RuntimeException("Failed to serialize closure", e);
       }
-
-      final ProcessBuilder processBuilder = new ProcessBuilder(java.toString(), "-cp", classPath)
-          .directory(workdir.toFile());
+      
+      final String absoluteClassPath =
+          Arrays.stream(classPath.split(File.pathSeparator))
+              .map(cp -> Paths.get(cp).toAbsolutePath().toString())
+              .collect(Collectors.joining(File.pathSeparator));
+
+      final ProcessBuilder processBuilder =
+          new ProcessBuilder(java.toString(), "-cp", absoluteClassPath).directory(workdir.toFile());
 
       // Propagate -Xmx and -D.
       // Note: This is suboptimal because if the user has configured a max heap size we will effectively use that