diff --git a/packages/compiler-pico-c/src/frontend/preprocessor/interpreter/createInterpreterContext.ts b/packages/compiler-pico-c/src/frontend/preprocessor/interpreter/createInterpreterContext.ts
index 51f64c95..643e4899 100644
--- a/packages/compiler-pico-c/src/frontend/preprocessor/interpreter/createInterpreterContext.ts
+++ b/packages/compiler-pico-c/src/frontend/preprocessor/interpreter/createInterpreterContext.ts
@@ -11,6 +11,7 @@ import { clexer } from '../../parser/lexer/clexer';
 import { evalTokens } from './evalTokens';
 
 import { ExpressionResultTreeVisitor } from './ExpressionResultTreeVisitor';
+import { CInternalCompilerFsResolver } from '../../../fs';
 import { CPreprocessorError, CPreprocessorErrorCode } from '../grammar';
 
 export type CInterpreterScope = {
@@ -39,14 +40,14 @@ export const createInterpreterContext = ({
     defineMacro: (name: string, macro: CPreprocessorMacro) => {
       scope.macros[name] = macro;
     },
+
     appendFinalTokens: finalTokens => {
       reduced.push(...finalTokens);
     },
-    evalExpression: expression => {
-      const visitor = new ExpressionResultTreeVisitor(ctx);
 
-      return visitor.visit(expression).value;
-    },
+    evalExpression: expression =>
+      new ExpressionResultTreeVisitor(ctx).visit(expression).value,
+
     includeFile: path => {
       if (!fsIncludeResolver) {
         throw new CPreprocessorError(
@@ -59,7 +60,13 @@ export const createInterpreterContext = ({
       pipe(
         E.Do,
         E.bind('resolverOutput', () =>
-          fsIncludeResolver.read(currentFilePath)(path),
+          pipe(
+            new CInternalCompilerFsResolver().read()(path),
+            E.fold(
+              () => fsIncludeResolver.read(currentFilePath)(path),
+              E.right,
+            ),
+          ),
         ),
         E.bindW('tokens', ({ resolverOutput }) =>
           clexer({})(resolverOutput.content),
diff --git a/packages/compiler-pico-c/src/fs/CInternalCompilerFsResolver.ts b/packages/compiler-pico-c/src/fs/CInternalCompilerFsResolver.ts
new file mode 100644
index 00000000..be38cdf7
--- /dev/null
+++ b/packages/compiler-pico-c/src/fs/CInternalCompilerFsResolver.ts
@@ -0,0 +1,47 @@
+import * as E from 'fp-ts/Either';
+
+import {
+  CPreprocessorError,
+  CPreprocessorErrorCode,
+} from '../frontend/preprocessor/grammar/CPreprocessorError';
+
+import type {
+  CInterpreterIncludeResolver,
+  CInterpreterSourceFile,
+  CInterpreterSourcePath,
+} from '../frontend/preprocessor';
+
+import { STD_ARG_CONTENT_HEADER } from './stdarg.h';
+
+export class CInternalCompilerFsResolver
+  implements CInterpreterIncludeResolver
+{
+  read =
+    () =>
+    (
+      path: CInterpreterSourcePath,
+    ): E.Either<CPreprocessorError, CInterpreterSourceFile> => {
+      const vfsFile = CInternalCompilerFsResolver.FILES[path.filename];
+
+      if (!path.system || !vfsFile) {
+        return E.left(
+          new CPreprocessorError(
+            CPreprocessorErrorCode.CANNOT_INCLUDE_FILE,
+            null,
+            {
+              name: path.filename,
+            },
+          ),
+        );
+      }
+
+      return E.right({
+        absolutePath: path.filename,
+        content: vfsFile,
+      });
+    };
+
+  private static FILES = {
+    'stdarg.h': STD_ARG_CONTENT_HEADER,
+  };
+}
diff --git a/packages/compiler-pico-c/src/fs/index.ts b/packages/compiler-pico-c/src/fs/index.ts
new file mode 100644
index 00000000..f12ab3a1
--- /dev/null
+++ b/packages/compiler-pico-c/src/fs/index.ts
@@ -0,0 +1,2 @@
+export * from './CInternalCompilerFsResolver';
+export * from './stdarg.h';
diff --git a/packages/compiler-pico-c/src/fs/stdarg.h.ts b/packages/compiler-pico-c/src/fs/stdarg.h.ts
new file mode 100644
index 00000000..5e9801d0
--- /dev/null
+++ b/packages/compiler-pico-c/src/fs/stdarg.h.ts
@@ -0,0 +1,5 @@
+export const STD_ARG_CONTENT_HEADER = /* c */ `
+  #define va_start(v, l)	__builtin_va_start(v, l)
+  #define va_end(v)	__builtin_va_end(v)
+  #define va_arg(v,l)	__builtin_va_arg(v, l)
+`;