diff -r 91af2c697345 -r ff09c95d9e44 src/EditProduct.cpp
--- a/src/EditProduct.cpp	Mon May 02 16:40:41 2022 +0200
+++ b/src/EditProduct.cpp	Mon May 02 21:09:48 2022 +0200
@@ -401,7 +401,7 @@
 		    product->fermentables.append(f);
 		}
 		qDebug() << "fermentables" << product->fermentables.size() << percentcheck;
-		if (percentcheck == 0) {
+		if (percentcheck == 0 && product->fermentables.size()) {
 		    /* Missing percentages, fix it. */
 		    double total = 0;
 		    for (int i = 0; i < product->fermentables.size(); i++) {