diff --git a/amount.cc b/amount.cc
index 8771e944..729d12f5 100644
--- a/amount.cc
+++ b/amount.cc
@@ -408,7 +408,7 @@ amount_t& amount_t::operator*=(const amount_t& amt)
 
 amount_t& amount_t::operator/=(const amount_t& amt)
 {
-  if (! amt.quantity)
+  if (! amt.quantity || ! amt)
     throw amount_error("Divide by zero");
   else if (! quantity)
     return *this;