diff --git a/rest-api-client.sh b/rest-api-client.sh
index ed27935869dd70543d86b6b245d64e528548269b..dbfb0440f2f7dde85c340b70b9bf6f35ec95bf33 100644
--- a/rest-api-client.sh
+++ b/rest-api-client.sh
@@ -14,6 +14,7 @@
 # 2020-02-07  v0.2  axel.hahn@iml.unibe.ch  BETABETA
 # 2020-02-12  v0.4  axel.hahn@iml.unibe.ch  Caching
 # 2020-03-02  v0.5  axel.hahn@iml.unibe.ch  a few more response check functions
+# 2021-01-21  v0.6  axel.hahn@iml.unibe.ch  add Content-type in request header
 # ======================================================================
 
 # --- fetch incoming params
@@ -22,7 +23,7 @@
   ApiUrl=$3
   Body="$4"
 
-  http_cfg__about="Bash REST API client v0.5"
+  http_cfg__about="Bash REST API client v0.6"
   typeset -i http_cfg__debug=0
   typeset -i http_cfg__cacheTtl=0
   http_cfg__cacheDir=/var/tmp/http-cache
@@ -185,6 +186,7 @@ EOH
             -A "${http_cfg__UA}" \
             -w "${http_curl__writeout}" \
             -H 'Accept: application/json' \
+            -H 'Content-type: application/json' \
             ${http_req__auth} \
             -i "${http_req__fullurl}" \
             -X "${http_req__method}"
@@ -193,6 +195,7 @@ EOH
             -A "${http_cfg__UA}" \
             -w "${http_curl__writeout}" \
             -H 'Accept: application/json' \
+            -H 'Content-type: application/json' \
             ${http_req__auth} \
             -i "${http_req__fullurl}" \
             -X "${http_req__method}" \