diff --git a/canopen/objectdictionary/__init__.py b/canopen/objectdictionary/__init__.py
index fa694c56..a44a963e 100644
--- a/canopen/objectdictionary/__init__.py
+++ b/canopen/objectdictionary/__init__.py
@@ -484,8 +484,8 @@ def decode_phys(self, value: int) -> Union[int, bool, float, str, bytes]:
 
     def encode_phys(self, value: Union[int, bool, float, str, bytes]) -> int:
         if self.data_type in INTEGER_TYPES:
-            value /= self.factor
-            value = int(round(value))
+            if self.factor != 1:
+                value = round(value / self.factor)
         return value
 
     def decode_desc(self, value: int) -> str:
diff --git a/test/test_od.py b/test/test_od.py
index 9ab0e187..28d7637b 100644
--- a/test/test_od.py
+++ b/test/test_od.py
@@ -182,6 +182,35 @@ def test_phys(self):
         self.assertAlmostEqual(var.decode_phys(128), 12.8)
         self.assertEqual(var.encode_phys(-0.1), -1)
 
+    def test_phys_factor_1_int64_roundtrip(self):
+        """int64 values must survive encode_phys when factor is 1."""
+        var = od.ODVariable("Test UNSIGNED64", 0x1000)
+        var.data_type = od.UNSIGNED64
+        value = 0x55554444AAAABBBB
+        self.assertEqual(var.encode_phys(value), value)
+
+    def test_phys_factor_1_preserves_int(self):
+        """encode_phys with factor=1 must not convert int to float."""
+        var = od.ODVariable("Test INTEGER32", 0x1000)
+        var.data_type = od.INTEGER32
+        self.assertIsInstance(var.encode_phys(42), int)
+
+    def test_phys_factor_1000_rounds(self):
+        """Existing rounding behaviour with integer factor != 1 is preserved."""
+        var = od.ODVariable("Test INTEGER32", 0x1000)
+        var.data_type = od.INTEGER32
+        var.factor = 1000
+        # 5555 / 1000 = 5.555 → round → 6
+        self.assertEqual(var.encode_phys(5555), 6)
+
+    def test_phys_float_factor(self):
+        """Float factor still works via float division + round."""
+        var = od.ODVariable("Test INTEGER16", 0x1000)
+        var.data_type = od.INTEGER16
+        var.factor = 0.5
+        # 10 / 0.5 = 20
+        self.assertEqual(var.encode_phys(10), 20)
+
     def test_desc(self):
         var = od.ODVariable("Test UNSIGNED8", 0x1000)
         var.data_type = od.UNSIGNED8