--- a/TypeConverter.st	Sat Jan 28 11:59:58 2017 +0100
+++ b/TypeConverter.st	Sun Jan 29 02:26:51 2017 +0100
@@ -723,18 +723,22 @@
                 time isNil ifTrue:[
                     ''
                 ] ifFalse:[
-                    (fmt := aFormatString) isNil ifTrue:[
-                        timeClass = TimeDuration ifTrue:[
-                            time isInteger ifTrue:[
-                                "backward compatibility - show integer time as seconds"
-                                time := time seconds.
+                    time isString ifTrue:[
+                        time "/ not strictly ok, bit we don't want to get a DNU...
+                    ] ifFalse:[
+                        (fmt := aFormatString) isNil ifTrue:[
+                            timeClass = TimeDuration ifTrue:[
+                                time isInteger ifTrue:[
+                                    "backward compatibility - show integer time as seconds"
+                                    time := time seconds.
+                                ].
+                                fmt := time formatForPrinting.
+                            ] ifFalse:[
+                                fmt := timeClass defaultFormatString
                             ].
-                            fmt := time formatForPrinting.
-                        ] ifFalse:[
-                            fmt := timeClass defaultFormatString
                         ].
-                    ].
-                    time printStringFormat:fmt language:langOrNil
+                        time printStringFormat:fmt language:langOrNil
+                    ]
                 ]]
 
         putBlock: