diff --git a/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/utils/FHIRPathEngine.java b/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/utils/FHIRPathEngine.java
index ace7041d3..a5f43da2e 100644
--- a/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/utils/FHIRPathEngine.java
+++ b/org.hl7.fhir.r4/src/main/java/org/hl7/fhir/r4/utils/FHIRPathEngine.java
@@ -22,6 +22,7 @@ import org.fhir.ucum.UcumException;
 import org.hl7.fhir.exceptions.DefinitionException;
 import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.exceptions.PathEngineException;
+import org.hl7.fhir.instance.model.api.IIdType;
 import org.hl7.fhir.r4.conformance.ProfileUtilities;
 import org.hl7.fhir.r4.context.IWorkerContext;
 import org.hl7.fhir.r4.context.IWorkerContext.ValidationResult;
@@ -894,7 +895,9 @@ public class FHIRPathEngine {
   }
 
   public String convertToString(Base item) {
-    if (item.isPrimitive()) {
+    if (item instanceof IIdType) {
+      return ((IIdType)item).getIdPart();
+    } else if (item.isPrimitive()) {
       return item.primitiveValue();
     } else if (item instanceof Quantity) {
       Quantity q = (Quantity) item;
diff --git a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/test/FHIRPathTests.java b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/test/FHIRPathTests.java
index b0b065f60..5a803584d 100644
--- a/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/test/FHIRPathTests.java
+++ b/org.hl7.fhir.r4/src/test/java/org/hl7/fhir/r4/test/FHIRPathTests.java
@@ -295,4 +295,16 @@ public class FHIRPathTests {
     assertEquals(DUMMY_CONSTANT_1, result.get(0).primitiveValue());
     assertEquals(DUMMY_CONSTANT_2, result.get(1).primitiveValue());
   }
+
+
+  @Test
+  public void testEvaluateToString_Id() {
+    Patient input = new Patient();
+    input.setId(new IdType("http://base/Patient/123/_history/222"));
+    String actual = fp.evaluateToString(input, "Patient.id");
+    assertEquals("123", actual);
+
+  }
+
+
 }
\ No newline at end of file
diff --git a/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/utils/FHIRPathEngine.java b/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/utils/FHIRPathEngine.java
index 1ec7ed7ca..15d82473c 100644
--- a/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/utils/FHIRPathEngine.java
+++ b/org.hl7.fhir.r4b/src/main/java/org/hl7/fhir/r4b/utils/FHIRPathEngine.java
@@ -22,6 +22,7 @@ import org.fhir.ucum.UcumException;
 import org.hl7.fhir.exceptions.DefinitionException;
 import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.exceptions.PathEngineException;
+import org.hl7.fhir.instance.model.api.IIdType;
 import org.hl7.fhir.r4b.conformance.ProfileUtilities;
 import org.hl7.fhir.r4b.context.IWorkerContext;
 import org.hl7.fhir.r4b.context.IWorkerContext.ValidationResult;
@@ -890,7 +891,9 @@ public class FHIRPathEngine {
   }
 
   public String convertToString(Base item) {
-    if (item.isPrimitive()) {
+    if (item instanceof IIdType) {
+      return ((IIdType)item).getIdPart();
+    } else if (item.isPrimitive()) {
       return item.primitiveValue();
     } else if (item instanceof Quantity) {
       Quantity q = (Quantity) item;
diff --git a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
index cd27d44ce..3e6797757 100644
--- a/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
+++ b/org.hl7.fhir.r5/src/main/java/org/hl7/fhir/r5/utils/FHIRPathEngine.java
@@ -22,6 +22,7 @@ import org.fhir.ucum.UcumException;
 import org.hl7.fhir.exceptions.DefinitionException;
 import org.hl7.fhir.exceptions.FHIRException;
 import org.hl7.fhir.exceptions.PathEngineException;
+import org.hl7.fhir.instance.model.api.IIdType;
 import org.hl7.fhir.r5.conformance.profile.ProfileUtilities;
 import org.hl7.fhir.r5.conformance.profile.ProfileUtilities.SourcedChildDefinitions;
 import org.hl7.fhir.r5.context.ContextUtilities;
@@ -952,7 +953,9 @@ public class FHIRPathEngine {
   }
 
   public String convertToString(Base item) {
-    if (item.isPrimitive()) {
+    if (item instanceof IIdType) {
+      return ((IIdType)item).getIdPart();
+    } else if (item.isPrimitive()) {
       return item.primitiveValue();
     } else if (item instanceof Quantity) {
       Quantity q = (Quantity) item;