diff --git a/pint/delegates/formatter/_compound_unit_helpers.py b/pint/delegates/formatter/_compound_unit_helpers.py
index 01e71d896..d6970b12e 100644
--- a/pint/delegates/formatter/_compound_unit_helpers.py
+++ b/pint/delegates/formatter/_compound_unit_helpers.py
@@ -254,9 +254,15 @@ def prepare_compount_unit(
         out = unit._units.items()
     else:
         out = unit
-    
+
     # out: unit_name, unit_exponent
 
+    if len(out) == 0:
+        if "~" in spec:
+            return ([], [])
+        else:
+            return ([("dimensionless", 1)], [])
+
     if "~" in spec:
         if registry is None:
             raise ValueError(
diff --git a/pint/testsuite/test_issues.py b/pint/testsuite/test_issues.py
index eb286d6c7..2fcc1f22c 100644
--- a/pint/testsuite/test_issues.py
+++ b/pint/testsuite/test_issues.py
@@ -1260,10 +1260,16 @@ def test_issue1772(given, expected):
 def test_issue2007():
     ureg = UnitRegistry()
     q = ureg.Quantity(1, "")
-    assert f"{q:P}" == '1 dimensionless'
-    assert f"{q:C}" == '1 dimensionless'
-    assert f"{q:D}" == '1 dimensionless'
-    assert f"{q:H}" == '1 dimensionless'
-    # assert f"{q:L}" == '1\\ dimensionless'
-    assert f"{q:Lx}" == '\\SI[]{1}{}'
-    assert f"{q:~P}" == '1'
\ No newline at end of file
+    assert f"{q:P}" == "1 dimensionless"
+    assert f"{q:C}" == "1 dimensionless"
+    assert f"{q:D}" == "1 dimensionless"
+    assert f"{q:H}" == "1 dimensionless"
+
+    assert f"{q:L}" == "1\\ \\mathrm{dimensionless}"
+    #  L returned '1\\ dimensionless' in pint 0.23
+
+    assert f"{q:Lx}" == "\\SI[]{1}{}"
+    assert f"{q:~P}" == "1"
+    assert f"{q:~C}" == "1"
+    assert f"{q:~D}" == "1"
+    assert f"{q:~H}" == "1"