diff --git a/DeThunk/src/header_preprocessor.py b/DeThunk/src/header_preprocessor.py
index 3268ecb..8c173f2 100644
--- a/DeThunk/src/header_preprocessor.py
+++ b/DeThunk/src/header_preprocessor.py
@@ -105,7 +105,7 @@ def process(path_to_file: str):
                         is_template,
                         is_empty,
                     )
-                    class_keyword_pos, _ = StrUtil.find_m(line, 'class ', 'struct ', 'union ')
+                    class_keyword_pos, _ = StrUtil.find_mb(line, 'class ', 'struct ', 'union ')
                     assert class_keyword_pos != -1, f"path = {path_to_file}, line = '{line}'"
 
                     if not is_empty:
diff --git a/DeThunk/src/header_processor.py b/DeThunk/src/header_processor.py
index 2ade8ac..b80a37c 100644
--- a/DeThunk/src/header_processor.py
+++ b/DeThunk/src/header_processor.py
@@ -302,7 +302,7 @@ class reference_wrapper {
             if not in_forward_declaration_list:
                 founded_cl = CppUtil.find_class_definition(line)
                 if founded_cl:
-                    class_keyword_pos, _ = StrUtil.find_m(line, 'class ', 'struct ', 'union ')
+                    class_keyword_pos, _ = StrUtil.find_mb(line, 'class ', 'struct ', 'union ')
                     assert class_keyword_pos != -1, f"path = {path_to_file}, line = '{line}'"
 
                     if not stripped_line.endswith('{};'):
diff --git a/DeThunk/src/util/cpp_language.py b/DeThunk/src/util/cpp_language.py
index 2cab70b..879a253 100644
--- a/DeThunk/src/util/cpp_language.py
+++ b/DeThunk/src/util/cpp_language.py
@@ -18,7 +18,7 @@ def find_class_definition(line: str) -> str | None:
     # KEYWORD A {
     # KEYWORD A { ... }; (in single line)
 
-    keyword_pos, keyword = StrUtil.find_m(line, 'enum class ', 'class ', 'struct ', 'union ')
+    keyword_pos, keyword = StrUtil.find_mb(line, 'enum class ', 'class ', 'struct ', 'union ')
     if keyword_pos == -1 or keyword == 'enum class ':
         return None
 
@@ -67,7 +67,7 @@ def find_class_forward_declaration(line: str) -> ForwardDeclaration | None:
     if namespace_pos != -1 and left_brace_pos != -1:
         namespace_decl = line[namespace_pos + len('namespace') : left_brace_pos].strip()
 
-    keyword_pos, keyword = StrUtil.find_m(line, 'class ', 'struct ', 'union ')
+    keyword_pos, keyword = StrUtil.find_mb(line, 'class ', 'struct ', 'union ')
     if keyword_pos == -1:
         return None
 
diff --git a/DeThunk/src/util/string.py b/DeThunk/src/util/string.py
index 793cbc2..6d1862f 100644
--- a/DeThunk/src/util/string.py
+++ b/DeThunk/src/util/string.py
@@ -19,6 +19,20 @@ def endswith_m(con: str, *args) -> bool:
     return False
 
 
+def find_mb(con: str, *args) -> int:  # bounded
+    r_pos = -1
+    r_arg = None
+    for arg in args:
+        matched = re.search(rf'\b{re.escape(arg)}\b', con)
+        if not matched:
+            continue
+        pos = matched.start()
+        if pos != -1 and (r_pos == -1 or pos < r_pos):
+            r_pos = pos
+            r_arg = arg
+    return r_pos, r_arg
+
+
 def find_m(con: str, *args) -> int:
     r_pos = -1
     r_arg = None