diff --git a/src/lob_hlpr/hlpr.py b/src/lob_hlpr/hlpr.py
index 087d914..ba316fb 100644
--- a/src/lob_hlpr/hlpr.py
+++ b/src/lob_hlpr/hlpr.py
@@ -260,6 +260,8 @@ def parse_dmc(dmc):
             # This: MPP-M0011554-OR019504_1-00781
             article_number = chunks.pop(1)
             # Changes to MPP-OR019504_1-00781
+        if chunks[0] != "MPP":
+            raise ValueError(f"Invalid DMC format: {dmc}, must start with MPP")
         # We want the OR019504 part
         erp_prod_number = chunks[0] + "-" + re.split("_", chunks[1])[0]
 
diff --git a/tests/test_lob_hlpr.py b/tests/test_lob_hlpr.py
index 2256734..2e422e8 100644
--- a/tests/test_lob_hlpr.py
+++ b/tests/test_lob_hlpr.py
@@ -26,6 +26,8 @@ def test_parse_dmc_fail():
     """Test failing branches of the parse_dmc function."""
     with pytest.raises(IndexError):
         hlp.parse_dmc("MPP-OR023282_1")
+    with pytest.raises(ValueError):
+        hlp.parse_dmc("PP-OR023282_1")
 
 
 # A bit of looking through a hex file and manual parsing allows me to provide