diff --git a/stim/biomodels/network.h b/stim/biomodels/network.h
index 7eb71c4..ac364ad 100644
--- a/stim/biomodels/network.h
+++ b/stim/biomodels/network.h
@@ -105,7 +105,12 @@ class network{
 			}
 
 			length = length_sum;						//store the total length
-			return radius_sum / length;					//return the average radius of the fiber
+
+			//if the total length is zero, store a radius of zero
+			if(length == 0)
+				return 0;
+			else
+				return radius_sum / length;					//return the average radius of the fiber
 		}
 
 		std::string str(){
--
libgit2 0.21.4