diff --git a/namelists/icon_atmosphere_real-from-dwd-ana.namelist b/namelists/icon_atmosphere_real-from-dwd-ana.namelist
index 94eb814ec1e29a0f329951c2ba2e33609cd82f2f..d05040fa82ff6cc2ddc4c911aaa9130b9195830b 100644
--- a/namelists/icon_atmosphere_real-from-dwd-ana.namelist
+++ b/namelists/icon_atmosphere_real-from-dwd-ana.namelist
@@ -12,11 +12,11 @@
 /
 
 &time_nml
-    dt_restart = %checkpoint_time%
+    dt_restart = '%checkpoint_time%'
 /
 
 &io_nml
-    dt_checkpoint = %checkpoint_time%
+    dt_checkpoint = '%checkpoint_time%'
 /
 
 &nwp_phy_nml