diff --git a/xoptics/dcm.py b/xoptics/dcm.py
index 333fb21..71e7f12 100755
--- a/xoptics/dcm.py
+++ b/xoptics/dcm.py
@@ -38,7 +38,7 @@ class Double_Crystal_Mono:
 
     def wait_for_valid_value(self):
         tval = np.nan
-        while not np.isfinite(tval)
+        while not np.isfinite(tval):
             tval = self.energy_rbk.get()
         return(tval)