diff --git a/ptypy/schema/ptypy_xmcd_calc_param.json b/ptypy/schema/ptypy_xmcd_calc_param.json
index cc05118..44604e7 100644
--- a/ptypy/schema/ptypy_xmcd_calc_param.json
+++ b/ptypy/schema/ptypy_xmcd_calc_param.json
@@ -3,11 +3,11 @@
   "properties": {
     "scan_number_lcp": {
       "type": "integer",
-      "minimum": "0"
+      "minimum": 0
     },
     "scan_number_rcp": {
       "type": "integer",
-      "minimum": "0"
+      "minimum": 0
     },
     "input_dir": {
       "type": "string",