diff --git a/src/libs/ifc/schema/multisize_measurements/v0.5.1.xsd b/src/libs/ifc/schema/multisize_measurements/v0.5.1.xsd
index b4ebbc349..cf3689c46 100644
--- a/src/libs/ifc/schema/multisize_measurements/v0.5.1.xsd
+++ b/src/libs/ifc/schema/multisize_measurements/v0.5.1.xsd
@@ -11,7 +11,7 @@
         <xs:element name="dimensions">
           <xs:complexType>
             <xs:sequence>
-              <xs:element name="dimension" minOccurs="0" maxOccurs="3">
+              <xs:element name="dimension" minOccurs="1" maxOccurs="3">
                 <xs:complexType>
                   <xs:sequence>
                     <xs:element name="labels" minOccurs="0" maxOccurs="1">