diff --git a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
index 4a2aaed1a..bb1cb8393 100644
--- a/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
+++ b/org.hl7.fhir.validation/src/main/java/org/hl7/fhir/validation/instance/InstanceValidator.java
@@ -4311,7 +4311,7 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
         StructureDefinition sdt = context.fetchTypeDefinition(type);
         StructureDefinition tt = sdt;
         while (tt != null) {
-          if (tt.getBaseDefinition().equals(sd.getUrl())) {
+          if (sd.getUrl().equals(tt.getBaseDefinition())) {
             return sdt;
           }
           tt = context.fetchResource(StructureDefinition.class, tt.getBaseDefinition());