diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ced216a7..467fc2f1 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -68,6 +68,7 @@ jobs:
       run: |
         python scripts/check_pragma_once.py include
         python scripts/check_undef.py src
+        python scripts/check_binding_retval.py
     - name: Unit Test with Coverage
       run: bash run_tests.sh
     - name: Upload coverage reports to Codecov
diff --git a/README.md b/README.md
index b0e7d9da..1664ded7 100644
--- a/README.md
+++ b/README.md
@@ -200,6 +200,19 @@ And these are the results of the primes benchmark on Intel i5-12400F, WSL (Ubunt
 
 Submit a pull request to add your project here.
 
+## Code Quality
+
+pocketpy maintains code quality through automated checks:
+
+- **Binding Return Value Check**: Ensures all Python binding functions properly set return values
+  ```bash
+  python scripts/check_binding_retval.py
+  ```
+- **Pragma Once Check**: Validates header file include guards
+- **Define/Undef Check**: Ensures balanced macro definitions
+
+These checks run automatically in CI/CD pipeline.
+
 ## Contribution
 
 All kinds of contributions are welcome.
diff --git a/docs/check_binding_retval.md b/docs/check_binding_retval.md
new file mode 100644
index 00000000..dbd8d8db
--- /dev/null
+++ b/docs/check_binding_retval.md
@@ -0,0 +1,175 @@
+# Binding Return Value Checker
+
+## Overview
+
+The `check_binding_retval.py` script is a static analysis tool that validates Python binding functions in the pocketpy codebase. It ensures that all functions bound to Python properly set return values before returning `true`.
+
+## Purpose
+
+In pocketpy's C API, when a binding function returns `true`, it indicates successful execution. According to the API conventions, the function MUST set a return value through one of these methods:
+
+1. **Direct assignment** using `py_new*` functions:
+   ```c
+   py_newint(py_retval(), 42);
+   return true;
+   ```
+
+2. **Setting None** explicitly:
+   ```c
+   py_newnone(py_retval());
+   return true;
+   ```
+
+3. **Using assignment**:
+   ```c
+   py_assign(py_retval(), some_value);
+   return true;
+   ```
+
+4. **Calling functions** that set `py_retval()` internally:
+   ```c
+   bool ok = py_import("module_name");  // Sets py_retval() on success
+   if(ok) return true;
+   ```
+
+## Usage
+
+### Basic Usage
+
+Run the checker on default directories (`src/bindings` and `src/modules`):
+
+```bash
+python scripts/check_binding_retval.py
+```
+
+### Verbose Mode
+
+Enable verbose output for debugging:
+
+```bash
+python scripts/check_binding_retval.py --verbose
+```
+
+### Custom Directories
+
+Check specific directories:
+
+```bash
+python scripts/check_binding_retval.py --dirs src/bindings src/modules src/custom
+```
+
+## Exit Codes
+
+- `0`: No issues found (success)
+- `1`: Issues found (binding functions missing return value assignment)
+- `2`: Script error (e.g., file access error)
+
+## Integration
+
+The checker is integrated into the CI/CD pipeline through the GitHub Actions workflow. It runs automatically on:
+
+- Push events
+- Pull request events
+
+The check is part of the "Run Script Check" step in `.github/workflows/main.yml`.
+
+## What It Checks
+
+The tool analyzes all functions that are bound to Python through:
+
+- `py_bindfunc()`
+- `py_bind()`
+- `py_bindmagic()`
+- `py_bindmethod()`
+- `py_bindproperty()`
+
+For each bound function, it verifies that:
+
+1. If the function contains `return true` statements
+2. There are corresponding assignments to `py_retval()`
+3. Comments are excluded from analysis (to avoid false positives)
+
+## Functions That Set py_retval() Internally
+
+The checker recognizes these functions that internally set `py_retval()`:
+
+- `py_import()` - Sets py_retval() to the imported module on success
+- `py_call()` - Sets py_retval() to the call result
+- `py_iter()` - Sets py_retval() to the iterator
+- `py_str()` - Sets py_retval() to string representation
+- `py_repr()` - Sets py_retval() to repr string
+- `py_getattr()` - Sets py_retval() to attribute value
+- `py_next()` - Sets py_retval() to next value
+- `py_getitem()` - Sets py_retval() to the item
+- `py_vectorcall()` - Sets py_retval() to call result
+
+## Example Issues
+
+### Issue: Missing Return Value
+
+```c
+static bool my_function(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    // Do some work...
+    return true;  // BUG: Should set py_retval() before returning!
+}
+```
+
+**Fix:**
+
+```c
+static bool my_function(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    // Do some work...
+    py_newnone(py_retval());  // Set return value to None
+    return true;
+}
+```
+
+### Correct: Using py_new* Functions
+
+```c
+static bool add_numbers(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(2);
+    py_i64 a = py_toint(py_arg(0));
+    py_i64 b = py_toint(py_arg(1));
+    py_newint(py_retval(), a + b);  // Sets return value
+    return true;
+}
+```
+
+### Correct: Calling Functions That Set py_retval()
+
+```c
+static bool import_module(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    int res = py_import(py_tostr(py_arg(0)));  // Sets py_retval() on success
+    if(res == -1) return false;
+    if(res) return true;  // py_retval() already set by py_import
+    return ImportError("module not found");
+}
+```
+
+## False Positives
+
+The checker may occasionally report false positives for:
+
+1. **Helper functions** that are bound but shouldn't set return values (rare)
+2. **Complex control flow** where the return value is set conditionally
+
+If you encounter a false positive, verify that:
+1. The function is actually a Python-bound callable
+2. The return value is properly set in all code paths leading to `return true`
+
+## Maintenance
+
+When adding new patterns or functions that set `py_retval()` internally:
+
+1. Update the `RETVAL_SETTING_FUNCTIONS` set in `check_binding_retval.py`
+2. Add corresponding test cases
+3. Update this documentation
+
+## Related Documentation
+
+- [pocketpy C API Documentation](https://pocketpy.dev/c-api/)
+- [Binding Functions Guide](https://pocketpy.dev/c-api/bindings/)
diff --git a/run_tests.sh b/run_tests.sh
index 6b2c46ef..5cdb79b5 100644
--- a/run_tests.sh
+++ b/run_tests.sh
@@ -2,6 +2,10 @@ set -e
 
 python prebuild.py
 
+# Run static analysis checks
+echo "Running static analysis checks..."
+python scripts/check_binding_retval.py || { echo "Binding return value check failed"; exit 1; }
+
 SRC=$(find src/ -name "*.c")
 
 clang -std=c11 --coverage -O1 -Wfatal-errors -o main src2/main.c $SRC -Iinclude -DPK_ENABLE_OS=1 -lm -ldl -DNDEBUG
diff --git a/scripts/check_binding_retval.py b/scripts/check_binding_retval.py
new file mode 100755
index 00000000..1c078e45
--- /dev/null
+++ b/scripts/check_binding_retval.py
@@ -0,0 +1,312 @@
+#!/usr/bin/env python3
+"""
+Static analysis tool to check Python binding functions for missing py_retval() assignments.
+
+This tool checks whether Python binding functions properly set return values before returning true.
+According to pocketpy conventions, when a binding function returns true, it MUST either:
+1. Assign a value to py_retval() using py_new* functions, py_assign, etc.
+2. Set the return value to None using py_newnone(py_retval())
+3. Call a function that sets py_retval() internally (like py_import, py_call, py_iter, etc.)
+
+Usage:
+    python scripts/check_binding_retval.py [--verbose]
+    
+Exit codes:
+    0: No issues found
+    1: Issues found
+    2: Script error
+"""
+
+import os
+import re
+import sys
+import argparse
+from typing import List, Dict, Tuple, Set
+
+# Functions that set py_retval() internally
+RETVAL_SETTING_FUNCTIONS = {
+    'py_import',      # Sets py_retval() on success
+    'py_call',        # Sets py_retval() with result
+    'py_iter',        # Sets py_retval() with iterator
+    'py_str',         # Sets py_retval() with string representation
+    'py_repr',        # Sets py_retval() with repr string
+    'py_getattr',     # Sets py_retval() with attribute value
+    'py_next',        # Sets py_retval() with next value
+    'py_getitem',     # Sets py_retval() with item
+    'py_vectorcall',  # Sets py_retval() with call result
+}
+
+# Patterns that indicate py_retval() is being set
+RETVAL_PATTERNS = [
+    r'py_retval\(\)',                    # Direct py_retval() usage
+    r'py_new\w+\s*\(\s*py_retval\(\)',   # py_newint(py_retval(), ...)
+    r'py_assign\s*\(\s*py_retval\(\)',   # py_assign(py_retval(), ...)
+    r'\*py_retval\(\)\s*=',              # *py_retval() = ...
+]
+
+
+class BindingChecker:
+    """Checker for Python binding functions."""
+    
+    def __init__(self, verbose: bool = False):
+        self.verbose = verbose
+        self.issues: List[Dict] = []
+        
+    def log(self, message: str):
+        """Log message if verbose mode is enabled."""
+        if self.verbose:
+            print(f"[DEBUG] {message}")
+    
+    def find_c_files(self, *directories: str) -> List[str]:
+        """Find all .c files in the given directories."""
+        c_files = []
+        for directory in directories:
+            if not os.path.exists(directory):
+                self.log(f"Directory not found: {directory}")
+                continue
+            for root, _, files in os.walk(directory):
+                for file in files:
+                    if file.endswith('.c'):
+                        c_files.append(os.path.join(root, file))
+        return c_files
+    
+    def extract_functions(self, content: str) -> Dict[str, Dict]:
+        """Extract all bool-returning functions from C code."""
+        # Pattern to match bool-returning functions
+        pattern = r'(?:static\s+)?bool\s+(\w+)\s*\(([^)]*)\)\s*\{([^{}]*(?:\{[^{}]*\}[^{}]*)*)\}'
+        
+        functions = {}
+        for match in re.finditer(pattern, content, re.MULTILINE | re.DOTALL):
+            func_name = match.group(1)
+            func_params = match.group(2)
+            func_body = match.group(3)
+            full_func = match.group(0)
+            
+            functions[func_name] = {
+                'params': func_params,
+                'body': func_body,
+                'full': full_func,
+                'start_pos': match.start(),
+            }
+        
+        return functions
+    
+    def get_bound_functions(self, content: str) -> Set[str]:
+        """Find functions that are bound as Python callables."""
+        bound_funcs = set()
+        
+        # Binding patterns used in pocketpy
+        patterns = [
+            r'py_bindfunc\s*\([^,]+,\s*"[^"]+",\s*(\w+)\)',
+            r'py_bind\s*\([^,]+,\s*"[^"]*",\s*(\w+)\)',
+            r'py_bindmagic\s*\([^,]+,\s*\w+,\s*(\w+)\)',
+            r'py_bindmethod\s*\([^,]+,\s*"[^"]+",\s*(\w+)\)',
+            r'py_bindproperty\s*\([^,]+,\s*"[^"]+",\s*(\w+)',
+        ]
+        
+        for pattern in patterns:
+            for match in re.finditer(pattern, content):
+                func_name = match.group(1)
+                bound_funcs.add(func_name)
+                self.log(f"Found bound function: {func_name}")
+        
+        return bound_funcs
+    
+    def remove_comments(self, code: str) -> str:
+        """Remove C-style comments from code."""
+        # Remove single-line comments
+        code = re.sub(r'//.*?$', '', code, flags=re.MULTILINE)
+        # Remove multi-line comments
+        code = re.sub(r'/\*.*?\*/', '', code, flags=re.DOTALL)
+        return code
+    
+    def has_retval_usage(self, func_body: str) -> bool:
+        """Check if function body uses py_retval() in any form."""
+        # Remove comments to avoid false positives
+        code_without_comments = self.remove_comments(func_body)
+        
+        # Check for direct patterns
+        for pattern in RETVAL_PATTERNS:
+            if re.search(pattern, code_without_comments):
+                return True
+        
+        # Check for functions that set py_retval internally
+        for func in RETVAL_SETTING_FUNCTIONS:
+            if func + '(' in code_without_comments:
+                return True
+        
+        return False
+    
+    def analyze_return_statements(self, func_body: str, func_name: str) -> List[Dict]:
+        """Analyze return true statements in the function."""
+        lines = func_body.split('\n')
+        suspicious_returns = []
+        
+        for i, line in enumerate(lines):
+            # Look for "return true" statements
+            if re.search(r'\breturn\s+true\b', line):
+                # Get context (10 lines before the return)
+                start = max(0, i - 10)
+                context_lines = lines[start:i+1]
+                context = '\n'.join(context_lines)
+                
+                suspicious_returns.append({
+                    'line_num': i + 1,
+                    'line': line.strip(),
+                    'context': context,
+                })
+        
+        return suspicious_returns
+    
+    def check_function(self, func_name: str, func_info: Dict, filepath: str) -> bool:
+        """
+        Check if a bound function properly sets py_retval() before returning true.
+        Returns True if there's an issue, False otherwise.
+        """
+        func_body = func_info['body']
+        
+        # Skip if function doesn't return true
+        if 'return true' not in func_body:
+            self.log(f"Function {func_name} doesn't return true, skipping")
+            return False
+        
+        # Check if function has any py_retval usage
+        if self.has_retval_usage(func_body):
+            self.log(f"Function {func_name} uses py_retval(), OK")
+            return False
+        
+        # Found a potential issue
+        self.log(f"Function {func_name} returns true without py_retval()!")
+        
+        suspicious_returns = self.analyze_return_statements(func_body, func_name)
+        
+        issue = {
+            'file': filepath,
+            'function': func_name,
+            'full_code': func_info['full'],
+            'suspicious_returns': suspicious_returns,
+        }
+        
+        self.issues.append(issue)
+        return True
+    
+    def check_file(self, filepath: str) -> int:
+        """Check all bound functions in a file."""
+        self.log(f"Checking file: {filepath}")
+        
+        try:
+            with open(filepath, 'r', encoding='utf-8', errors='ignore') as f:
+                content = f.read()
+        except Exception as e:
+            print(f"Error reading {filepath}: {e}", file=sys.stderr)
+            return 0
+        
+        # Extract functions and find bound ones
+        functions = self.extract_functions(content)
+        bound_funcs = self.get_bound_functions(content)
+        
+        if not bound_funcs:
+            self.log(f"No bound functions found in {filepath}")
+            return 0
+        
+        issues_count = 0
+        for func_name in bound_funcs:
+            if func_name not in functions:
+                self.log(f"Bound function {func_name} not found in extracted functions")
+                continue
+            
+            if self.check_function(func_name, functions[func_name], filepath):
+                issues_count += 1
+        
+        return issues_count
+    
+    def check_directories(self, *directories: str) -> int:
+        """Check all C files in the given directories."""
+        c_files = self.find_c_files(*directories)
+        
+        if not c_files:
+            print("No C files found to check", file=sys.stderr)
+            return 0
+        
+        self.log(f"Found {len(c_files)} C files to check")
+        
+        total_issues = 0
+        for filepath in c_files:
+            issues = self.check_file(filepath)
+            total_issues += issues
+        
+        return total_issues
+    
+    def print_report(self):
+        """Print a detailed report of all issues found."""
+        if not self.issues:
+            print("✓ No issues found! All Python binding functions properly set py_retval().")
+            return
+        
+        print(f"\n{'='*80}")
+        print(f"Found {len(self.issues)} function(s) with potential issues:")
+        print(f"{'='*80}\n")
+        
+        for i, issue in enumerate(self.issues, 1):
+            print(f"Issue #{i}:")
+            print(f"  File: {issue['file']}")
+            print(f"  Function: {issue['function']}")
+            print(f"  Problem: Function returns true but doesn't set py_retval()")
+            print(f"\n  Function code:")
+            print("  " + "-" * 76)
+            for line in issue['full_code'].split('\n'):
+                print(f"  {line}")
+            print("  " + "-" * 76)
+            
+            if issue['suspicious_returns']:
+                print(f"\n  Found {len(issue['suspicious_returns'])} 'return true' statement(s):")
+                for ret in issue['suspicious_returns']:
+                    print(f"    Line {ret['line_num']}: {ret['line']}")
+            
+            print(f"\n{'='*80}\n")
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description='Check Python binding functions for missing py_retval() assignments',
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog=__doc__
+    )
+    parser.add_argument(
+        '--verbose', '-v',
+        action='store_true',
+        help='Enable verbose output for debugging'
+    )
+    parser.add_argument(
+        '--dirs',
+        nargs='+',
+        default=['src/bindings', 'src/modules'],
+        help='Directories to check (default: src/bindings src/modules)'
+    )
+    
+    args = parser.parse_args()
+    
+    # Create checker and run analysis
+    checker = BindingChecker(verbose=args.verbose)
+    
+    print("Checking Python binding functions for missing py_retval() assignments...")
+    print(f"Target directories: {', '.join(args.dirs)}")
+    print()
+    
+    try:
+        total_issues = checker.check_directories(*args.dirs)
+        checker.print_report()
+        
+        # Exit with appropriate code
+        sys.exit(1 if total_issues > 0 else 0)
+        
+    except Exception as e:
+        print(f"\nError during analysis: {e}", file=sys.stderr)
+        if args.verbose:
+            import traceback
+            traceback.print_exc()
+        sys.exit(2)
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tests/test_check_binding_retval.py b/tests/test_check_binding_retval.py
new file mode 100644
index 00000000..a9b1a790
--- /dev/null
+++ b/tests/test_check_binding_retval.py
@@ -0,0 +1,173 @@
+#!/usr/bin/env python3
+"""
+Test suite for check_binding_retval.py script.
+
+This test verifies that the binding return value checker correctly identifies
+issues in Python binding functions.
+"""
+
+import os
+import sys
+import tempfile
+import subprocess
+from pathlib import Path
+
+# Get the repository root
+REPO_ROOT = Path(__file__).parent.parent
+CHECKER_SCRIPT = REPO_ROOT / "scripts" / "check_binding_retval.py"
+
+
+def run_checker(test_dir):
+    """Run the checker on a test directory and return the exit code and output."""
+    result = subprocess.run(
+        [sys.executable, str(CHECKER_SCRIPT), "--dirs", test_dir],
+        capture_output=True,
+        text=True
+    )
+    return result.returncode, result.stdout, result.stderr
+
+
+def test_correct_binding():
+    """Test that correct bindings pass validation."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        test_file = Path(tmpdir) / "test_correct.c"
+        test_file.write_text("""
+#include "pocketpy/pocketpy.h"
+
+// Correct: sets py_retval() with py_newint
+static bool correct_function_1(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    py_newint(py_retval(), 42);
+    return true;
+}
+
+// Correct: sets py_retval() with py_newnone
+static bool correct_function_2(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(0);
+    py_newnone(py_retval());
+    return true;
+}
+
+// Correct: uses py_import which sets py_retval()
+static bool correct_function_3(int argc, py_Ref argv) {
+    int res = py_import("test");
+    if(res == 1) return true;
+    return false;
+}
+
+void register_correct() {
+    py_GlobalRef mod = py_newmodule("test");
+    py_bindfunc(mod, "f1", correct_function_1);
+    py_bindfunc(mod, "f2", correct_function_2);
+    py_bindfunc(mod, "f3", correct_function_3);
+}
+""")
+        
+        exit_code, stdout, stderr = run_checker(tmpdir)
+        assert exit_code == 0, f"Expected exit code 0, got {exit_code}\n{stdout}\n{stderr}"
+        assert "No issues found" in stdout, f"Expected success message\n{stdout}"
+        print("✓ test_correct_binding passed")
+
+
+def test_incorrect_binding():
+    """Test that incorrect bindings are detected."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        test_file = Path(tmpdir) / "test_incorrect.c"
+        test_file.write_text("""
+#include "pocketpy/pocketpy.h"
+
+// Incorrect: returns true without setting py_retval()
+static bool incorrect_function(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    // Missing py_retval() assignment
+    return true;
+}
+
+void register_incorrect() {
+    py_GlobalRef mod = py_newmodule("test");
+    py_bindfunc(mod, "bad", incorrect_function);
+}
+""")
+        
+        exit_code, stdout, stderr = run_checker(tmpdir)
+        assert exit_code == 1, f"Expected exit code 1, got {exit_code}\n{stdout}\n{stderr}"
+        assert "incorrect_function" in stdout, f"Expected to find function name\n{stdout}"
+        assert "potential issues" in stdout, f"Expected issues message\n{stdout}"
+        print("✓ test_incorrect_binding passed")
+
+
+def test_comments_ignored():
+    """Test that comments mentioning py_retval() don't cause false negatives."""
+    with tempfile.TemporaryDirectory() as tmpdir:
+        test_file = Path(tmpdir) / "test_comments.c"
+        test_file.write_text("""
+#include "pocketpy/pocketpy.h"
+
+// This function has comments about py_retval() but doesn't actually set it
+static bool buggy_function(int argc, py_Ref argv) {
+    PY_CHECK_ARGC(1);
+    // TODO: Should call py_retval() here
+    /* py_newint(py_retval(), 42); */
+    return true;  // BUG: Missing actual py_retval()
+}
+
+void register_buggy() {
+    py_GlobalRef mod = py_newmodule("test");
+    py_bindfunc(mod, "bug", buggy_function);
+}
+""")
+        
+        exit_code, stdout, stderr = run_checker(tmpdir)
+        assert exit_code == 1, f"Expected exit code 1, got {exit_code}\n{stdout}\n{stderr}"
+        assert "buggy_function" in stdout, f"Expected to find function name\n{stdout}"
+        print("✓ test_comments_ignored passed")
+
+
+def test_actual_codebase():
+    """Test that the actual codebase passes validation."""
+    src_bindings = REPO_ROOT / "src" / "bindings"
+    src_modules = REPO_ROOT / "src" / "modules"
+    
+    if not src_bindings.exists() or not src_modules.exists():
+        print("⊘ test_actual_codebase skipped (directories not found)")
+        return
+    
+    exit_code, stdout, stderr = run_checker(str(REPO_ROOT / "src"))
+    assert exit_code == 0, f"Actual codebase should pass validation\n{stdout}\n{stderr}"
+    print("✓ test_actual_codebase passed")
+
+
+def main():
+    """Run all tests."""
+    print("Running tests for check_binding_retval.py...")
+    print("=" * 80)
+    
+    tests = [
+        test_correct_binding,
+        test_incorrect_binding,
+        test_comments_ignored,
+        test_actual_codebase,
+    ]
+    
+    failed = 0
+    for test in tests:
+        try:
+            test()
+        except AssertionError as e:
+            print(f"✗ {test.__name__} failed: {e}")
+            failed += 1
+        except Exception as e:
+            print(f"✗ {test.__name__} error: {e}")
+            failed += 1
+    
+    print("=" * 80)
+    if failed == 0:
+        print(f"All {len(tests)} tests passed!")
+        return 0
+    else:
+        print(f"{failed}/{len(tests)} tests failed!")
+        return 1
+
+
+if __name__ == "__main__":
+    sys.exit(main())