diff --git a/lib/core.cpp b/lib/core.cpp
index 6ff5453..7fcf99e 100644
--- a/lib/core.cpp
+++ b/lib/core.cpp
@@ -1034,8 +1034,8 @@ auto operator*(const ScalarAffineFunction &a, const ScalarAffineFunction &b)
 		auto d0 = b.constant.value();
 		for (int i = 0; i < a.coefficients.size(); i++)
 		{
-			auto ci = b.coefficients[i];
-			auto xi = b.variables[i];
+			auto ci = a.coefficients[i];
+			auto xi = a.variables[i];
 			t._add_affine_term(xi, ci * d0);
 		}
 	}
diff --git a/tests/test_operator.py b/tests/test_operator.py
index e58be4a..0d5fbb0 100644
--- a/tests/test_operator.py
+++ b/tests/test_operator.py
@@ -96,7 +96,10 @@ def test_operator():
         vars[4],
         3 * vars[2],
         2 * vars[1] + vars[3],
+        2 * vars[2] + vars[3] + 5.0,
         13 * vars[4] * vars[4],
+        17 * vars[3] * vars[3] + 1.0,
+        17 * vars[3] * vars[5] + 3 * vars[1],
         11 * vars[5] * vars[5] + 7 * vars[1] + 3.0,
     ]
     exprs += [ExprBuilder(e) for e in exprs]
@@ -118,6 +121,9 @@ def test_operator():
                 continue
             expr = op(ei, ej)
             value = evaluate(expr, var_value_map)
+            flag = value == approx(op(expr_values[i], expr_values[j]))
+            if not flag:
+                k = 1
             assert value == approx(op(expr_values[i], expr_values[j]))
 
     op = truediv