diff --git a/semantic/src/main/kotlin/tools/samt/semantic/ConstraintBuilder.kt b/semantic/src/main/kotlin/tools/samt/semantic/ConstraintBuilder.kt
index d55b35cf..0bda554c 100644
--- a/semantic/src/main/kotlin/tools/samt/semantic/ConstraintBuilder.kt
+++ b/semantic/src/main/kotlin/tools/samt/semantic/ConstraintBuilder.kt
@@ -103,7 +103,7 @@ internal class ConstraintBuilder(private val controller: DiagnosticController) {
 
         try { Regex(pattern) } catch (e: Exception) {
             argument.reportError(controller) {
-                message("Invalid regex pattern")
+                message("Invalid regex pattern: '${e.message}'")
                 highlight(argument.location)
             }
             return null
diff --git a/semantic/src/test/kotlin/tools/samt/semantic/SemanticModelTest.kt b/semantic/src/test/kotlin/tools/samt/semantic/SemanticModelTest.kt
index 1a31c8da..2baf6e80 100644
--- a/semantic/src/test/kotlin/tools/samt/semantic/SemanticModelTest.kt
+++ b/semantic/src/test/kotlin/tools/samt/semantic/SemanticModelTest.kt
@@ -345,7 +345,9 @@ class SemanticModelTest {
             """.trimIndent()
             parseAndCheck(
                 source to listOf(
-                    "Error: Invalid regex pattern"
+                    "Error: Invalid regex pattern: 'Dangling meta character '+' near index 5\n" +
+                            "fo/+++!hi\n" +
+                            "     ^'"
                 )
             )
         }
diff --git a/specification/examples/debug/debug.samt b/specification/examples/debug/debug.samt
new file mode 100644
index 00000000..3b739358
--- /dev/null
+++ b/specification/examples/debug/debug.samt
@@ -0,0 +1,5 @@
+package debug.test
+
+record Foo {
+    name: String ("++")
+}
\ No newline at end of file
diff --git a/specification/examples/debug/samt.yaml b/specification/examples/debug/samt.yaml
new file mode 100644
index 00000000..96a38136
--- /dev/null
+++ b/specification/examples/debug/samt.yaml
@@ -0,0 +1,5 @@
+source: ./
+
+generators:
+  - name: kotlin-ktor-consumer
+    output: ./out