diff --git a/script_umdp3_checker/umdp3_checker_rules.py b/script_umdp3_checker/umdp3_checker_rules.py
index 5aea535b..964469a6 100644
--- a/script_umdp3_checker/umdp3_checker_rules.py
+++ b/script_umdp3_checker/umdp3_checker_rules.py
@@ -32,6 +32,12 @@
 # Declare version
 VERSION = "13.5.0"
 
+# Precompile regex statements
+_vars_declare = re.compile(r"^\s*(INTEGER|REAL|LOGICAL|CHARACTER|TYPE)\s*.*::\s*[A-Z_]+", re.IGNORECASE)
+_vars_cleaner = re.compile(r"^\s*(INTEGER|REAL|LOGICAL|CHARACTER|TYPE)\s*.*::\s*(.+)$", re.IGNORECASE)
+_consecutive_upper = re.compile(r"([A-Z]{2,})")
+_comment_declare = re.compile(r"!.*$")
+
 
 @dataclass
 class TestResult:
@@ -325,25 +331,29 @@ def lowercase_variable_names(self, lines: List[str]) -> TestResult:
         count = -1
         for count, line in enumerate(lines, 1):
             clean_line = self.remove_quoted(line)
-            clean_line = re.sub(r"!.*$", "", clean_line)
+            clean_line = _comment_declare.sub("", clean_line)
 
             # Simple check for UPPERCASE variable declarations
-            if re.search(
-                r"^\s*(INTEGER|REAL|LOGICAL|CHARACTER|TYPE)\s*.*::\s*[A-Z_]+",
-                clean_line,
-                re.IGNORECASE,
-            ):
-                clean_line = re.sub(
-                    r"^\s*(INTEGER|REAL|LOGICAL|CHARACTER|TYPE)\s*.*::\s*",
-                    "",
-                    clean_line,
-                )
-                if match := re.search(r"([A-Z]{2,})", clean_line):
-                    self.add_extra_error(f"UPPERCASE variable name : {match[1]}")
-                    failures += 1
-                    error_log = self.add_error_log(
-                        error_log, f"UPPERCASE variable name {match[1]}", count
-                    )
+            if _vars_declare.search(clean_line):
+                # Extract variable names part using capturing group
+                match_vars = _vars_cleaner.search(clean_line)
+                if match_vars:
+                    var_declarations = match_vars.group(2).strip()
+                    # Split by comma to get individual variable names
+                    var_names = var_declarations.split(",")
+
+                    for var_name in var_names:
+                        index = 1
+                        # Extract just the variable name (before = or ()
+                        var_name = re.split(r'[=(]', var_name)[0].strip()
+
+                        if _consecutive_upper.search(var_name):
+                            self.add_extra_error(f"UPPERCASE variable name : {var_name}")
+                            failures += 1
+                            error_log = self.add_error_log(
+                                error_log, f"UPPERCASE variable name {var_name}", count
+                            )
+                            index += 1
 
         output = f"Checked {count + 1} lines, found {failures} failures."
         return TestResult(