diff --git a/contrib/src/fl/rowlayoutpl.cpp b/contrib/src/fl/rowlayoutpl.cpp
index a1dd955c8c..92af22e862 100644
--- a/contrib/src/fl/rowlayoutpl.cpp
+++ b/contrib/src/fl/rowlayoutpl.cpp
@@ -433,6 +433,9 @@ void cbRowLayoutPlugin::ApplyLengthRatios( cbRowInfo* pRow )
     // look like total of mLetRatio's is 1.0, thus original
     // len. ratios are _preserved_:
 
+    if (pcntSum == 0.0)
+        pcntSum = 1.0;
+
     double unit = freeSpc / pcntSum;
 
     bool haveSquished = FALSE;