diff --git a/utils/prometheus-node-exporter-lua/Makefile b/utils/prometheus-node-exporter-lua/Makefile
index bab0fde12..18638b39e 100644
--- a/utils/prometheus-node-exporter-lua/Makefile
+++ b/utils/prometheus-node-exporter-lua/Makefile
@@ -5,7 +5,7 @@ include $(TOPDIR)/rules.mk
 
 PKG_NAME:=prometheus-node-exporter-lua
 PKG_VERSION:=2018.12.30
-PKG_RELEASE:=4
+PKG_RELEASE:=5
 
 PKG_MAINTAINER:=Etienne CHAMPETIER <champetier.etienne@gmail.com>
 PKG_LICENSE:=Apache-2.0
diff --git a/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/conntrack.lua b/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/conntrack.lua
index 93b26c266..1abb7a191 100644
--- a/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/conntrack.lua
+++ b/utils/prometheus-node-exporter-lua/files/usr/lib/lua/prometheus-collectors/conntrack.lua
@@ -1,8 +1,12 @@
 local function scrape()
-  metric("node_nf_conntrack_entries", "gauge", nil,
-    string.sub(get_contents("/proc/sys/net/netfilter/nf_conntrack_count"), 1, -2))
-  metric("node_nf_conntrack_entries_limit", "gauge", nil,
-    string.sub(get_contents("/proc/sys/net/netfilter/nf_conntrack_max"), 1, -2))
+  local count = get_contents("/proc/sys/net/netfilter/nf_conntrack_count")
+  local max = get_contents("/proc/sys/net/netfilter/nf_conntrack_max")
+  if count ~= "" then
+    metric("node_nf_conntrack_entries", "gauge", nil, string.sub(count, 1, -2))
+  end
+  if max ~= "" then
+    metric("node_nf_conntrack_entries_limit", "gauge", nil, string.sub(max, 1, -2))
+  end
 end
 
 return { scrape = scrape }