diff --git a/Model/Sorghum/Leaf.cpp b/Model/Sorghum/Leaf.cpp
index 9b64fa93d3..1fe38fa984 100644
--- a/Model/Sorghum/Leaf.cpp
+++ b/Model/Sorghum/Leaf.cpp
@@ -195,7 +195,7 @@ void Leaf::updateVars(void)
    dltNSenesced = 0.0;
 
    // leaf area
-   if(lai < 0.001)lai = 0.0;
+   if(lai < 0.0) { throw std::runtime_error("LAI < 0 !"); }
    lai += dltLAI;
 
    sLai += dltSlai;