diff --git a/core/deployment/src/main/java/io/quarkus/deployment/dev/ClassLoaderCompiler.java b/core/deployment/src/main/java/io/quarkus/deployment/dev/ClassLoaderCompiler.java
index 7195bf7c3d8fb..6d0467009f4ea 100644
--- a/core/deployment/src/main/java/io/quarkus/deployment/dev/ClassLoaderCompiler.java
+++ b/core/deployment/src/main/java/io/quarkus/deployment/dev/ClassLoaderCompiler.java
@@ -146,7 +146,7 @@ public ClassLoaderCompiler(ClassLoader classLoader,
                             new CompilationProvider.Context(
                                     i.getName(),
                                     classPathElements,
-                                    new File(i.getProjectDirectory()),
+                                    i.getProjectDirectory() == null ? null : new File(i.getProjectDirectory()),
                                     new File(sourcePath),
                                     new File(i.getClassesPath()),
                                     context.getSourceEncoding(),