diff --git a/liquidjava-verifier/src/main/java/liquidjava/api/CommandLineLauncher.java b/liquidjava-verifier/src/main/java/liquidjava/api/CommandLineLauncher.java
index 6a066f7b..e7efeff6 100644
--- a/liquidjava-verifier/src/main/java/liquidjava/api/CommandLineLauncher.java
+++ b/liquidjava-verifier/src/main/java/liquidjava/api/CommandLineLauncher.java
@@ -6,6 +6,7 @@
 
 import liquidjava.diagnostics.Diagnostics;
 import liquidjava.diagnostics.errors.CustomError;
+import liquidjava.diagnostics.warnings.CustomWarning;
 import liquidjava.processor.RefinementProcessor;
 import spoon.Launcher;
 import spoon.processing.ProcessingManager;
@@ -54,7 +55,11 @@ public static void launch(String... paths) {
         }
         launcher.getEnvironment().setNoClasspath(true);
         launcher.getEnvironment().setComplianceLevel(8);
-        launcher.run();
+
+        boolean buildSuccess = launcher.getModelBuilder().build();
+        if (!buildSuccess) {
+            diagnostics.add(new CustomWarning("Java compilation error detected. Verification might be affected."));
+        }
 
         final Factory factory = launcher.getFactory();
         final ProcessingManager processingManager = new QueueProcessingManager(factory);
diff --git a/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/CustomWarning.java b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/CustomWarning.java
new file mode 100644
index 00000000..22e5917d
--- /dev/null
+++ b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/CustomWarning.java
@@ -0,0 +1,20 @@
+package liquidjava.diagnostics.warnings;
+
+import spoon.reflect.cu.SourcePosition;
+
+/**
+ * Custom warning with a message
+ * 
+ * @see LJWarning
+ */
+public class CustomWarning extends LJWarning {
+
+    public CustomWarning(SourcePosition position, String message) {
+        super(message, position);
+    }
+
+    public CustomWarning(String message) {
+        super(message, null);
+    }
+
+}
diff --git a/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalClassNotFoundWarning.java b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalClassNotFoundWarning.java
index 86438b6b..356542f0 100644
--- a/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalClassNotFoundWarning.java
+++ b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalClassNotFoundWarning.java
@@ -1,6 +1,6 @@
 package liquidjava.diagnostics.warnings;
 
-import spoon.reflect.declaration.CtElement;
+import spoon.reflect.cu.SourcePosition;
 
 /**
  * Warning indicating that a class referenced in an external refinement was not found
@@ -11,8 +11,8 @@ public class ExternalClassNotFoundWarning extends LJWarning {
 
     private final String className;
 
-    public ExternalClassNotFoundWarning(CtElement element, String message, String className) {
-        super(message, element.getPosition());
+    public ExternalClassNotFoundWarning(SourcePosition position, String message, String className) {
+        super(message, position);
         this.className = className;
     }
 
diff --git a/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalMethodNotFoundWarning.java b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalMethodNotFoundWarning.java
index 60f20f17..c9f573ae 100644
--- a/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalMethodNotFoundWarning.java
+++ b/liquidjava-verifier/src/main/java/liquidjava/diagnostics/warnings/ExternalMethodNotFoundWarning.java
@@ -1,6 +1,6 @@
 package liquidjava.diagnostics.warnings;
 
-import spoon.reflect.declaration.CtElement;
+import spoon.reflect.cu.SourcePosition;
 
 /**
  * Warning indicating that a method referenced in an external refinement was not found
@@ -13,9 +13,9 @@ public class ExternalMethodNotFoundWarning extends LJWarning {
     private final String className;
     private final String[] overloads;
 
-    public ExternalMethodNotFoundWarning(CtElement element, String message, String methodName, String className,
+    public ExternalMethodNotFoundWarning(SourcePosition position, String message, String methodName, String className,
             String[] overloads) {
-        super(message, element.getPosition());
+        super(message, position);
         this.methodName = methodName;
         this.className = className;
         this.overloads = overloads;
diff --git a/liquidjava-verifier/src/main/java/liquidjava/processor/refinement_checker/ExternalRefinementTypeChecker.java b/liquidjava-verifier/src/main/java/liquidjava/processor/refinement_checker/ExternalRefinementTypeChecker.java
index a52ac891..7bd910b6 100644
--- a/liquidjava-verifier/src/main/java/liquidjava/processor/refinement_checker/ExternalRefinementTypeChecker.java
+++ b/liquidjava-verifier/src/main/java/liquidjava/processor/refinement_checker/ExternalRefinementTypeChecker.java
@@ -43,7 +43,7 @@ public <T> void visitCtInterface(CtInterface<T> intrface) {
             this.prefix = externalRefinements.get();
             if (!classExists(prefix)) {
                 String message = String.format("Could not find class '%s'", prefix);
-                diagnostics.add(new ExternalClassNotFoundWarning(intrface, message, prefix));
+                diagnostics.add(new ExternalClassNotFoundWarning(intrface.getPosition(), message, prefix));
                 return;
             }
             getRefinementFromAnnotation(intrface);
@@ -72,7 +72,7 @@ public <R> void visitCtMethod(CtMethod<R> method) {
                         prefix);
                 String[] overloads = getOverloads(targetType, method);
                 diagnostics.add(
-                        new ExternalMethodNotFoundWarning(method, message, method.getSignature(), prefix, overloads));
+                        new ExternalMethodNotFoundWarning(method.getPosition(), message, method.getSignature(), prefix, overloads));
             }
         } else {
             if (!methodExists(targetType, method)) {
@@ -80,7 +80,7 @@ public <R> void visitCtMethod(CtMethod<R> method) {
                         method.getType().getSimpleName(), method.getSignature(), prefix);
                 String[] overloads = getOverloads(targetType, method);
                 diagnostics.add(
-                        new ExternalMethodNotFoundWarning(method, message, method.getSignature(), prefix, overloads));
+                        new ExternalMethodNotFoundWarning(method.getPosition(), message, method.getSignature(), prefix, overloads));
                 return;
             }
         }