diff --git a/heka/files/encoder/es-json.toml b/heka/files/encoder/es-json.toml
index de86b21..c4c4659 100644
--- a/heka/files/encoder/es-json.toml
+++ b/heka/files/encoder/es-json.toml
@@ -1,5 +1,9 @@
 [encoder_{{ name }}]
 type = "ESJsonEncoder"
 index = "{{ values.index }}"
-es_index_from_timestamp = {{ values.es_index_from_timestamp }}
+
+{% if values.es_index_from_timestamp = 'True' %}
+es_index_from_timestamp = true
+{%- else -%}
+es_index_from_timestamp = false