diff --git a/hapi-fhir-validation/src/main/java/org/hl7/fhir/r4/validation/InstanceValidator.java b/hapi-fhir-validation/src/main/java/org/hl7/fhir/r4/validation/InstanceValidator.java
index 985d77a87b6..1b6517746d6 100644
--- a/hapi-fhir-validation/src/main/java/org/hl7/fhir/r4/validation/InstanceValidator.java
+++ b/hapi-fhir-validation/src/main/java/org/hl7/fhir/r4/validation/InstanceValidator.java
@@ -3538,7 +3538,9 @@ public class InstanceValidator extends BaseValidator implements IResourceValidat
     // all observations should have a subject, a performer, and a time
 
     bpCheck(errors, IssueType.INVALID, element.line(), element.col(), stack.getLiteralPath(), element.getNamedChild("subject") != null, "All observations should have a subject");
-    bpCheck(errors, IssueType.INVALID, element.line(), element.col(), stack.getLiteralPath(), element.getNamedChild("performer") != null, "All observations should have a performer");
+    List<Element> performer = new ArrayList();
+    element.getNamedChildren("performer", performer);
+    bpCheck(errors, IssueType.INVALID, element.line(), element.col(), stack.getLiteralPath(), !performer.isEmpty(), "All observations should have a performer");
     bpCheck(errors, IssueType.INVALID, element.line(), element.col(), stack.getLiteralPath(), element.getNamedChild("effectiveDateTime") != null || element.getNamedChild("effectivePeriod") != null,
         "All observations should have an effectiveDateTime or an effectivePeriod");
   }
diff --git a/hapi-fhir-validation/src/test/java/org/hl7/fhir/r4/validation/FhirInstanceValidatorR4Test.java b/hapi-fhir-validation/src/test/java/org/hl7/fhir/r4/validation/FhirInstanceValidatorR4Test.java
index 9bb949c1381..a9c9080e035 100644
--- a/hapi-fhir-validation/src/test/java/org/hl7/fhir/r4/validation/FhirInstanceValidatorR4Test.java
+++ b/hapi-fhir-validation/src/test/java/org/hl7/fhir/r4/validation/FhirInstanceValidatorR4Test.java
@@ -208,6 +208,23 @@ public class FhirInstanceValidatorR4Test {
 
 	}
 
+	/**
+	 * See #853
+	 */
+	@Test
+	public void testObservationsWithMultiplePerformers() {
+		Observation observation = new Observation();
+		observation.setStatus(ObservationStatus.FINAL);
+		observation.setCode(new CodeableConcept().addCoding(new Coding().setSystem("http://system").setCode("code")));
+		Practitioner p1 = new Practitioner();
+		Practitioner p2 = new Practitioner();
+		observation.addPerformer(new Reference(p1));
+		observation.addPerformer(new Reference(p2));
+
+		ValidationResult output = myVal.validateWithResult(observation);
+		List<SingleValidationMessage> errors = logResultsAndReturnNonInformationalOnes(output);
+		assertThat(errors, empty());
+	}
 
 	@Test
 	public void testBase64Invalid() {