diff --git a/src/constants.ts b/src/constants.ts
new file mode 100644
index 00000000..74519201
--- /dev/null
+++ b/src/constants.ts
@@ -0,0 +1,3 @@
+export const WOLLOK_EXTRA_STACK_TRACE_HEADER = 'Derived from TypeScript stack'
+
+export const WOLLOK_BASE_PACKAGE = 'wollok.'
\ No newline at end of file
diff --git a/src/index.ts b/src/index.ts
index 2e179bda..dd8e0bd9 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -19,6 +19,7 @@ function buildEnvironment(files: List<{ name: string, content: string }>, baseEn
   }), baseEnvironment)
 }
 
+export * from './constants'
 export * from './model'
 export * from './interpreter/runtimeModel'
 export {
diff --git a/src/interpreter/runtimeModel.ts b/src/interpreter/runtimeModel.ts
index 574da2b4..7b07dba4 100644
--- a/src/interpreter/runtimeModel.ts
+++ b/src/interpreter/runtimeModel.ts
@@ -1,3 +1,4 @@
+import { WOLLOK_BASE_PACKAGE, WOLLOK_EXTRA_STACK_TRACE_HEADER } from '../constants'
 import { v4 as uuid } from 'uuid'
 import { getPotentiallyUninitializedLazy } from '../decorators'
 import { get, is, last, List, match, raise, when } from '../extensions'
@@ -50,7 +51,7 @@ export class WollokException extends Error {
   get message(): string {
     const error: RuntimeObject = this.instance
     error.assertIsException()
-    return `${error.innerValue ? error.innerValue.message : error.get('message')?.innerString ?? ''}\n${this.wollokStack}\n     Derived from TypeScript stack`
+    return `${error.innerValue ? error.innerValue.message : error.get('message')?.innerString ?? ''}\n${this.wollokStack}\n     ${WOLLOK_EXTRA_STACK_TRACE_HEADER}`
   }
 
   // TODO: Do we need to take this into consideration for Evaluation.copy()? This might be inside Exception objects
@@ -152,6 +153,11 @@ export class Frame extends Context {
   override toString(): string {
     return `${this.description}(${this.sourceInfo})`
   }
+
+  isCustom(): boolean {
+    const module = this.node.ancestors.find(ancestor => ancestor.is(Module)) as Module
+    return !module?.fullyQualifiedName?.startsWith(WOLLOK_BASE_PACKAGE) && !this.node.is(Environment)
+  }
 }
 
 
diff --git a/src/validator.ts b/src/validator.ts
index 91226c28..3d9c1302 100644
--- a/src/validator.ts
+++ b/src/validator.ts
@@ -18,6 +18,7 @@
 // - Level could be different for the same Expectation on different nodes
 // - Problem could know how to convert to string, receiving the interpolation function (so it can be translated). This could let us avoid having parameters.
 // - Good default for simple problems, but with a config object for more complex, so we know what is each parameter
+import { WOLLOK_BASE_PACKAGE } from './constants'
 import { count, TypeDefinition, duplicates, is, isEmpty, last, List, match, notEmpty, when } from './extensions'
 // - Unified problem type
 import { Assignment, Body, Catch, Class, Code, Describe, Entity, Expression, Field, If, Import,
@@ -703,7 +704,7 @@ const usesReservedWords = (node: Class | Singleton | Variable | Field | Paramete
   const parent = node.ancestors.find(ancestor => ancestor.is(Package)) as Package | undefined
   const wordsReserved = LIBRARY_PACKAGES.flatMap(libPackage => node.environment.getNodeByFQN<Package>(libPackage).members.map(_ => _.name))
   wordsReserved.push('wollok')
-  return !!parent && !parent.fullyQualifiedName.includes('wollok.') && wordsReserved.includes(node.name)
+  return !!parent && !parent.fullyQualifiedName.includes(WOLLOK_BASE_PACKAGE) && wordsReserved.includes(node.name)
 }
 
 const supposedToReturnValue = (node: Node): boolean => match(node.parent)(
diff --git a/src/wre/lang.ts b/src/wre/lang.ts
index b55e0c62..31bc9856 100644
--- a/src/wre/lang.ts
+++ b/src/wre/lang.ts
@@ -11,7 +11,8 @@ const lang: Natives = {
   Exception: {
     *initialize(self: RuntimeObject): Execution<void> {
       const stackTraceElements: RuntimeObject[] = []
-      for(const frame of this.frameStack.slice(0, -1)){
+      const customFrames = this.frameStack.slice(0, -1).filter(frame => frame.isCustom())
+      for(const frame of customFrames){
         const stackTraceElement = yield* this.send('createStackTraceElement', self, yield* this.reify(frame.description), yield* this.reify(frame.sourceInfo))
         stackTraceElements.unshift(stackTraceElement!)
       }