diff --git a/pixm-connector-service/src/main/java/net/ihe/gazelle/business/provider/IhePatientResourceProvider.java b/pixm-connector-service/src/main/java/net/ihe/gazelle/business/provider/IhePatientResourceProvider.java
index 8ca812ce8321883ac2bc9d4be771a1d6f0f403e1..fd2fa683f07eb597e1330a4236c210737153d459 100644
--- a/pixm-connector-service/src/main/java/net/ihe/gazelle/business/provider/IhePatientResourceProvider.java
+++ b/pixm-connector-service/src/main/java/net/ihe/gazelle/business/provider/IhePatientResourceProvider.java
@@ -267,13 +267,13 @@ public class IhePatientResourceProvider implements IResourceProvider {
 
     private List<String> createTargetSystemListFromParam(StringAndListParam targetSystemParam) {
         List<String> targetSystemList = new ArrayList<>();
-        if (targetSystemParam == null || targetSystemParam.size() == 0) {
-            throw new UnprocessableEntityException(TARGET_SYSTEM_NOT_FOUND);
-        }
-        for (StringOrListParam listParam : targetSystemParam.getValuesAsQueryTokens()) {
-            List<StringParam> queryStrings = listParam.getValuesAsQueryTokens();
-            buildTargetSystemList(queryStrings, targetSystemList);
+        if (targetSystemParam != null && targetSystemParam.size() > 0) {
+            for (StringOrListParam listParam : targetSystemParam.getValuesAsQueryTokens()) {
+                List<StringParam> queryStrings = listParam.getValuesAsQueryTokens();
+                buildTargetSystemList(queryStrings, targetSystemList);
+            }
         }
+
         return targetSystemList;
     }