--- a/configmix/config.py	Wed Nov 10 01:42:15 2021 +0100
+++ b/configmix/config.py	Wed Nov 10 01:53:23 2021 +0100
@@ -367,6 +367,17 @@
         else:
             return s
 
+    def getfirstfloatvar_s(self, varname, default=_MARKER):
+        """Get a (possibly substituted) variable and convert text to a
+        float
+
+        """
+        s = self.getfirstvar_s(varname, default)
+        if isinstance(s, self._TEXTTYPE):
+            return float(s)
+        else:
+            return s
+
     def _split_ns(self, s):
         nameparts = s.split(self._NS_SEPARATOR, 1)
         if len(nameparts) == 1: