diff --git a/fhirpathpy/engine/invocations/equality.py b/fhirpathpy/engine/invocations/equality.py
index 2960fb0..fc17903 100644
--- a/fhirpathpy/engine/invocations/equality.py
+++ b/fhirpathpy/engine/invocations/equality.py
@@ -182,7 +182,7 @@ def lt(ctx, a, b):
     if isinstance(a0, nodes.FP_Type):
         if (
             isinstance(a0, nodes.FP_TimeBase)
-            and a0.compare(b0) == 0
+            and a0.compare(b0) is None
             and a0._precision != b0._precision
         ):
             return None
@@ -204,7 +204,7 @@ def gt(ctx, a, b):
     if isinstance(a0, nodes.FP_Type):
         if (
             isinstance(a0, nodes.FP_TimeBase)
-            and a0.compare(b0) == 0
+            and a0.compare(b0) is None
             and a0._precision != b0._precision
         ):
             return None
@@ -226,7 +226,7 @@ def lte(ctx, a, b):
     if isinstance(a0, nodes.FP_Type):
         if (
             isinstance(a0, nodes.FP_TimeBase)
-            and a0.compare(b0) == 0
+            and a0.compare(b0) is None
             and a0._precision != b0._precision
         ):
             return None
@@ -248,7 +248,7 @@ def gte(ctx, a, b):
     if isinstance(a0, nodes.FP_Type):
         if (
             isinstance(a0, nodes.FP_TimeBase)
-            and a0.compare(b0) == 0
+            and a0.compare(b0) is None
             and a0._precision != b0._precision
         ):
             return None
diff --git a/fhirpathpy/engine/nodes.py b/fhirpathpy/engine/nodes.py
index b0a0a3b..b34f19b 100644
--- a/fhirpathpy/engine/nodes.py
+++ b/fhirpathpy/engine/nodes.py
@@ -394,7 +394,7 @@ def compare(self, otherDateTime):
                     return 1
                 if normalized_thisdt_list[i] < normalized_otherdt_list[i]:
                     return -1
-            return 0
+            return None
 
         thisDateTimeInt = self._getDateTimeInt()
         otherDateTimeInt = otherDateTime._getDateTimeInt()