diff --git a/kibot/bom/units.py b/kibot/bom/units.py
index ff28eeb7..b900a866 100644
--- a/kibot/bom/units.py
+++ b/kibot/bom/units.py
@@ -86,8 +86,8 @@ def get_prefix(prefix):
     # Unknown, we shouldn't get here because the regex matched
     # BUT: I found that sometimes unexpected things happend, like mu matching micro and then we reaching this code
     #      Now is fixed, but I can't be sure some bizarre case is overlooked
-    logger.error('Unknown prefix, please report')  # pragma: no cover (Internal)
-    return 1, ''  # pragma: no cover (Internal)
+    logger.error('Unknown prefix, please report')
+    return 1, ''
 
 
 def group_string(group):  # Return a reg-ex string for a list of values
diff --git a/tests/test_plot/test_misc_2.py b/tests/test_plot/test_misc_2.py
index 0593da9a..d4769f20 100644
--- a/tests/test_plot/test_misc_2.py
+++ b/tests/test_plot/test_misc_2.py
@@ -22,6 +22,7 @@ from kibot.registrable import RegOutput, RegFilter
 from kibot.misc import (MISSING_TOOL, WRONG_INSTALL, BOM_ERROR, DRC_ERROR, ERC_ERROR, PDF_PCB_PRINT, CMD_PCBNEW_PRINT_LAYERS,
                         KICAD2STEP_ERR)
 from kibot.bom.columnlist import ColumnList
+from kibot.bom.units import get_prefix
 from kibot.__main__ import detect_kicad
 from kibot.kicad.config import KiConf
 
@@ -268,3 +269,9 @@ def test_step_fail(test_dir, caplog, monkeypatch):
     assert e.type == SystemExit
     assert e.value.code == KICAD2STEP_ERR
     assert "Failed to create Step file, error 10" in caplog.text
+
+
+def test_unknown_prefix(caplog):
+    with context.cover_it(cov):
+        get_prefix('y')
+    assert 'Unknown prefix, please report' in caplog.text