diff --git a/CHANGELOG.md b/CHANGELOG.md
index a7cdc7bd..2ef6a742 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -20,6 +20,7 @@ and this project is in the process of adopting [Semantic Versioning](https://sem
 - Introduced a maven based build process to automate the manual tasks required for merging PRs and making releases. 
   This change does not affect the content of the ontologies.
 - Replaced (hopefully) all occurrences of `hr` as a symbol for `unit:HR` with `h`.
+- Add `unit:NUM-PER-MilliL`
 
 ## [2.1.44] - 2024-10-27
 
diff --git a/src/main/rdf/vocab/unit/VOCAB_QUDT-UNITS-ALL-v2.1.ttl b/src/main/rdf/vocab/unit/VOCAB_QUDT-UNITS-ALL-v2.1.ttl
index 22af03ab..86088835 100644
--- a/src/main/rdf/vocab/unit/VOCAB_QUDT-UNITS-ALL-v2.1.ttl
+++ b/src/main/rdf/vocab/unit/VOCAB_QUDT-UNITS-ALL-v2.1.ttl
@@ -32288,6 +32288,20 @@ unit:NUM-PER-MilliGM
   rdfs:isDefinedBy <http://qudt.org/2.1/vocab/unit> ;
   rdfs:label "Number per milligram"@en .
 
+unit:NUM-PER-MilliL
+  a qudt:Unit ;
+  dcterms:description "Count of an entity or phenomenon occurrence in one thousandth of the SI unit of volume (litre)."@en ;
+  qudt:conversionMultiplier 1000000.0 ;
+  qudt:conversionMultiplierSN 1.0E6 ;
+  qudt:exactMatch unit:NUM-PER-MilliL ;
+  qudt:hasDimensionVector qkdv:A0E0L-3I0M0H0T0D0 ;
+  qudt:hasQuantityKind quantitykind:NumberDensity ;
+  qudt:symbol "/mL" ;
+  qudt:ucumCode "/mL"^^qudt:UCUMcs ;
+  qudt:ucumCode "{#}.mL-1"^^qudt:UCUMcs ;
+  rdfs:isDefinedBy <http://qudt.org/2.1/vocab/unit> ;
+  rdfs:label "Number per Millilitre"@en .
+
 unit:NUM-PER-MilliM3
   a qudt:Unit ;
   qudt:conversionMultiplier 1000000000.0 ;