diff --git a/Whatsapp_Chat_Exporter/utility.py b/Whatsapp_Chat_Exporter/utility.py
index fc97d33..04a0c67 100644
--- a/Whatsapp_Chat_Exporter/utility.py
+++ b/Whatsapp_Chat_Exporter/utility.py
@@ -123,11 +123,9 @@ def readable_to_bytes(size_str: str) -> int:
         # If the string is purely numeric, assume it's in bytes
         return int(size_str)
     if not match:
-        raise ValueError("Invalid size format. Expected format like '10MB', '1024GB', or '512'.")
+        raise ValueError("Invalid size format for size_str. Expected format like '10MB', '1024GB', or '512'.")
     unit = ''.join(filter(str.isalpha, size_str)).strip()
     number = ''.join(c for c in size_str if c.isdigit() or c == '.').strip()
-    if unit not in SIZE_UNITS:
-        raise ValueError("Invalid input for size_str. Example: 1024GB")
     return int(float(number) * SIZE_UNITS[unit])
 
 
diff --git a/tests/test_utility.py b/tests/test_utility.py
index c4d57f2..8ea2af4 100644
--- a/tests/test_utility.py
+++ b/tests/test_utility.py
@@ -66,13 +66,13 @@ class TestReadableToBytes:
         assert readable_to_bytes(" 1 MB") == 1024**2
 
     def test_invalid_unit(self):
-        with pytest.raises(ValueError, match="Invalid input for size_str"):
+        with pytest.raises(ValueError, match="Invalid size format for size_str"):
             readable_to_bytes("100X")
             readable_to_bytes("A100")
             readable_to_bytes("100$$$$$")
 
     def test_invalid_number(self):
-        with pytest.raises(ValueError, match="Invalid input for size_str"):
+        with pytest.raises(ValueError, match="Invalid size format for size_str"):
             readable_to_bytes("ABC KB")
 
     def test_missing_unit(self):