diff --git a/openwisp-monitoring/files/monitoring.agent b/openwisp-monitoring/files/monitoring.agent
index 78457a8..1fc9e7d 100755
--- a/openwisp-monitoring/files/monitoring.agent
+++ b/openwisp-monitoring/files/monitoring.agent
@@ -151,9 +151,7 @@ send_data() {
 			fi
 			filename="$TMP_DIR/$filename"
 			# check if the data file exist
-			if [ -f "$filename" ]; then
-				data=$(cat "$filename")
-			else
+			if ! [ -f "$filename" ]; then
 				[ "$VERBOSE_MODE" -eq "1" ] && logger -s "data file $filename not found." \
 					-p daemon.info
 				continue
@@ -176,7 +174,13 @@ send_data() {
 					break
 				fi
 				# send data
-				response_code=$($CURL_COMMAND -H "Content-Type: application/json" -d "$data" "$url")
+				if [ "$VERBOSE_MODE" -eq "1" ]; then
+					printf "data="
+					cat "$filename"
+					set -x
+				fi
+				response_code=$($CURL_COMMAND -H "Content-Type: application/json" -d "@$filename" "$url")
+				set +x
 				if [ "$response_code" = "200" ]; then
 					success=$((success + 1))
 					if [ "$VERBOSE_MODE" -eq "1" ]; then