diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8de430..b706c76 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -3,6 +3,9 @@ All notable changes to this project will be documented in this file.
 This project adheres to [Semantic Versioning](http://semver.org/) and [Keep a changelog](https://github.com/olivierlacan/keep-a-changelog).
 
 ## [Unreleased](https://github.com/idealista/nginx_role/tree/develop)
+### Fixed
+- *[#65](https://github.com/idealista/nginx_role/issues/65) No value passed error in prometheus metrics* @jmonterrubio
+
 ## [2.1.0](https://github.com/idealista/nginx_role/tree/2.1.0) (2019-09-09)
 [Full Changelog](https://github.com/idealista/nginx_role/compare/2.1.0...2.0.1)
 ### Fixed
diff --git a/templates/metrics/prometheus.conf.j2 b/templates/metrics/prometheus.conf.j2
index 59e1a2f..ef5b0ef 100644
--- a/templates/metrics/prometheus.conf.j2
+++ b/templates/metrics/prometheus.conf.j2
@@ -85,16 +85,20 @@ log_by_lua_block {
                 upstream_bytes_sent = getWithIndex(ngx.var.upstream_bytes_sent, idx)
             end
             http_upstream_requests:inc(1, {addr, upstream_status})
-            http_upstream_response_time:observe(tonumber(upstream_response_time), {addr})
-            http_upstream_header_time:observe(tonumber(upstream_header_time), {addr})
+            if upstream_response_time ~= nil and tonumber(upstream_response_time) ~= nil then
+                http_upstream_response_time:observe(tonumber(upstream_response_time), {addr})
+            end
+            if http_upstream_header_time ~= nil and tonumber(http_upstream_header_time) ~= nil then
+                http_upstream_header_time:observe(tonumber(upstream_header_time), {addr})
+            end
             -- ngx.config.nginx_version >= 1011004
-            if upstream_first_byte_time ~= nil then
+            if upstream_first_byte_time ~= nil and tonumber(upstream_first_byte_time) ~= nil then
                 http_upstream_first_byte_time:observe(tonumber(upstream_first_byte_time), {addr})
             end
-            if upstream_connect_time ~= nil then
+            if upstream_connect_time ~= nil and tonumber(upstream_connect_time) ~= nil then
                 http_upstream_connect_time:observe(tonumber(upstream_connect_time), {addr})
             end
-            if upstream_session_time ~= nil then
+            if upstream_session_time ~= nil and tonumber(upstream_session_time) ~= nil then
                 http_upstream_session_time:observe(tonumber(upstream_session_time), {addr})
             end
             if upstream_bytes_received ~= nil then