diff --git a/netbox/extras/api/customfields.py b/netbox/extras/api/customfields.py
index fc83b33e5..5554df924 100644
--- a/netbox/extras/api/customfields.py
+++ b/netbox/extras/api/customfields.py
@@ -29,34 +29,47 @@ class CustomFieldsSerializer(serializers.BaseSerializer):
 
         for field_name, value in data.items():
 
-            cf = custom_fields[field_name]
+            try:
+                cf = custom_fields[field_name]
+            except KeyError:
+                raise ValidationError(
+                    "Invalid custom field for {} objects: {}".format(content_type, field_name)
+                )
 
-            # Validate custom field name
-            if field_name not in custom_fields:
-                raise ValidationError("Invalid custom field for {} objects: {}".format(content_type, field_name))
+            # Data validation
+            if value not in [None, '']:
 
-            # Validate boolean
-            if cf.type == CF_TYPE_BOOLEAN and value not in [True, False, 1, 0]:
-                raise ValidationError("Invalid value for boolean field {}: {}".format(field_name, value))
+                # Validate boolean
+                if cf.type == CF_TYPE_BOOLEAN and value not in [True, False, 1, 0]:
+                    raise ValidationError(
+                        "Invalid value for boolean field {}: {}".format(field_name, value)
+                    )
 
-            # Validate date
-            if cf.type == CF_TYPE_DATE:
-                try:
-                    datetime.strptime(value, '%Y-%m-%d')
-                except ValueError:
-                    raise ValidationError("Invalid date for field {}: {}. (Required format is YYYY-MM-DD.)".format(
-                        field_name, value
-                    ))
+                # Validate date
+                if cf.type == CF_TYPE_DATE:
+                    try:
+                        datetime.strptime(value, '%Y-%m-%d')
+                    except ValueError:
+                        raise ValidationError(
+                            "Invalid date for field {}: {}. (Required format is YYYY-MM-DD.)".format(field_name, value)
+                        )
 
-            # Validate selected choice
-            if cf.type == CF_TYPE_SELECT:
-                try:
-                    value = int(value)
-                except ValueError:
-                    raise ValidationError("{}: Choice selections must be passed as integers.".format(field_name))
-                valid_choices = [c.pk for c in cf.choices.all()]
-                if value not in valid_choices:
-                    raise ValidationError("Invalid choice for field {}: {}".format(field_name, value))
+                # Validate selected choice
+                if cf.type == CF_TYPE_SELECT:
+                    try:
+                        value = int(value)
+                    except ValueError:
+                        raise ValidationError(
+                            "{}: Choice selections must be passed as integers.".format(field_name)
+                        )
+                    valid_choices = [c.pk for c in cf.choices.all()]
+                    if value not in valid_choices:
+                        raise ValidationError(
+                            "Invalid choice for field {}: {}".format(field_name, value)
+                        )
+
+            elif cf.required:
+                raise ValidationError("Required field {} cannot be empty.".format(field_name))
 
         # Check for missing required fields
         missing_fields = []