diff --git a/src/util/variant.test.c b/src/util/variant.test.c
index 12299720b..37aa3f77e 100644
--- a/src/util/variant.test.c
+++ b/src/util/variant.test.c
@@ -30,6 +30,16 @@ static void test_fractions(CuTest *tc) {
     CuAssertIntEquals(tc, -1, frac_sign(frac_make(-1, 1)));
     CuAssertIntEquals(tc, -1, frac_sign(frac_make(1, -1)));
     CuAssertIntEquals(tc, 0, frac_sign(frac_make(0, 1)));
+
+    /* we reduce large integers by calculating the gcd */
+    a = frac_make(480000, 3000);
+    CuAssertIntEquals(tc, 160, a.sa[0]);
+    CuAssertIntEquals(tc, 1, a.sa[1]);
+
+    /* if num is too big for a short, and the gcd is 1, we cheat: */
+    a = frac_make(480001, 3000);
+    CuAssertIntEquals(tc, 32000, a.sa[0]);
+    CuAssertIntEquals(tc, 200, a.sa[1]);
 }
 
 CuSuite *get_variant_suite(void)