diff --git a/src/example/browser/cql4browsers.js b/src/example/browser/cql4browsers.js
index b3a6b7a67..c9e6910a8 100644
--- a/src/example/browser/cql4browsers.js
+++ b/src/example/browser/cql4browsers.js
@@ -43831,8 +43831,9 @@
     }
 
     Results.prototype.recordPatientResult = function(patient_ctx, resultName, result) {
-      var base, patientId;
-      patientId = patient_ctx.patient.id();
+      var base, p, patientId;
+      p = patient_ctx.patient;
+      patientId = typeof p.getId === 'function' ? p.getId() : p.id();
       if ((base = this.patientResults)[patientId] == null) {
         base[patientId] = {};
       }
diff --git a/src/runtime/results.coffee b/src/runtime/results.coffee
index e44fe4032..b2a542d9e 100644
--- a/src/runtime/results.coffee
+++ b/src/runtime/results.coffee
@@ -5,7 +5,11 @@ module.exports.Results = class Results
     @localIdPatientResultsMap = {}
 
   recordPatientResult: (patient_ctx, resultName, result) ->
-    patientId = patient_ctx.patient.id()
+    p = patient_ctx.patient
+    # NOTE: From now on prefer getId() over id() because some data models may have an id property
+    # that is not a string (e.g., FHIR) -- so reserve getId() for the API (and expect a string
+    # representation) but leave id() for data-model specific formats.
+    patientId = if typeof p.getId == 'function' then p.getId() else p.id()
     @patientResults[patientId] ?= {}
     @patientResults[patientId][resultName] = result
     @localIdPatientResultsMap[patientId] = patient_ctx.getAllLocalIds()