diff --git a/gtk/details.c b/gtk/details.c
index 188d4facc..2e0d98796 100644
--- a/gtk/details.c
+++ b/gtk/details.c
@@ -791,7 +791,7 @@ refreshInfo( struct DetailsImpl * di, tr_torrent ** torrents, int n )
             str = none;
         else {
             char unver[64], total[64];
-            const double ratio = ( 100.0 * ( haveValid + haveUnchecked ) )  / leftUntilDone;
+            const double ratio = 100.0 * ( leftUntilDone ? ( haveValid + haveUnchecked ) / leftUntilDone : 1 );
             tr_strlsize( total, haveUnchecked + haveValid, sizeof( total ) );
             tr_strlsize( unver, haveUnchecked,             sizeof( unver ) );
             if( haveUnchecked )
diff --git a/qt/details.cc b/qt/details.cc
index d7690fda4..a5983c2b6 100644
--- a/qt/details.cc
+++ b/qt/details.cc
@@ -267,7 +267,8 @@ Details :: refresh( )
     if( !haveVerified && !haveUnverified )
         string = none;
     else {
-        QString pct = locale.toString( 100.0*((sizeWhenDone-leftUntilDone)/sizeWhenDone), 'f', 2 );
+        const double d = 100.0 * ( sizeWhenDone ? ( sizeWhenDone - leftUntilDone ) / sizeWhenDone : 1 );
+        QString pct = locale.toString( d, 'f', 2 );
         if( !haveUnverified )
             string = tr( "%1 (%2%)" )
                          .arg( Utils :: sizeToString( haveVerified + haveUnverified ) )