diff --git a/gaboshlib/g_calc.sh b/gaboshlib/g_calc.sh
index c2269f9..04605dd 100644
--- a/gaboshlib/g_calc.sh
+++ b/gaboshlib/g_calc.sh
@@ -25,8 +25,20 @@ function g_calc {
   # send calculation and read result
   echo "$1" >&${g_fd_bc_in}
   read -u ${g_fd_bc_out} g_calc_result
-  g_calc_result=${g_calc_result//-./-0.}
-  g_calc_result=${g_calc_result//./0.}
+
+  # check if there is a output
+  if [ -z $g_calc_result ]
+  then
+    echo "${FUNCNAME} $@" 1>&2
+    unset g_calc_result
+    return 1
+  fi 
+
+  # fix bc outpur -> change for example .224 to 0.224 and -.224 to -0.224
+  [[ $g_calc_result  == "."* ]] && g_calc_result="0$g_calc_result"
+  [[ $g_calc_result  == "-."* ]] && g_calc_result="-0.${g_calc_result#-.}"
+
+  # check output
   if ! g_num_valid_number $g_calc_result
   then
     echo "${FUNCNAME} $@" 1>&2