diff --git a/src_main/math/pimathmatrix.h b/src_main/math/pimathmatrix.h
index f9c3e973..09e6905c 100644
--- a/src_main/math/pimathmatrix.h
+++ b/src_main/math/pimathmatrix.h
@@ -527,11 +527,11 @@ inline PIMathVector<Type> operator *(const PIMathMatrix<Type> & fm,
 	PIMathVector<Type> tv(r);
 	if (c != sv.size()) return tv;
 	Type t;
-	for (uint i = 0; i < r; ++i) {
+	for (uint j = 0; j < r; ++j) {
 		t = Type(0);
-		for (uint j = 0; j < c; ++j)
-			t += fm.element(j, i) * sv[j];
-		tv[i] = t;
+		for (uint i = 0; i < c; ++i)
+			t += fm.element(j, i) * sv[i];
+		tv[j] = t;
 	}
 	return tv;
 }