gistfile1.txt

diff --git a/src/6model/reprs/P6bigint.c b/src/6model/reprs/P6bigint.c
index 533766e9..d810a1c9 100644
--- a/src/6model/reprs/P6bigint.c
+++ b/src/6model/reprs/P6bigint.c
@@ -6,7 +6,7 @@
 
 /* A forced 64-bit version of mp_get_long, since on some platforms long is
  * not all that long. */
-static MVMuint64 mp_get_int64(MVMThreadContext *tc, mp_int * a) {
+static MVMuint64 mp_get_int64(MVMThreadContext *tc, mp_int * a, int sign) {
     int i, bits;
     MVMuint64 res;
 
@@ -15,7 +15,7 @@ static MVMuint64 mp_get_int64(MVMThreadContext *tc, mp_int * a) {
     }
 
     bits = mp_count_bits(a);
-    if (bits > 64) {
+    if (bits > (sign ? 63 : 64)) {
         MVM_exception_throw_adhoc(tc, "Cannot unbox %d bit wide bigint into native integer", bits);
     }
 
@@ -92,10 +92,10 @@ static MVMint64 get_int(MVMThreadContext *tc, MVMSTable *st, MVMObject *root, vo
     if (MVM_BIGINT_IS_BIG(body)) {
         mp_int *i = body->u.bigint;
         if (MP_NEG == SIGN(i)) {
-            return -mp_get_int64(tc, i);
+            return -mp_get_int64(tc, i, 1);
         }
         else {
-            return mp_get_int64(tc, i);
+            return mp_get_int64(tc, i, 1);
         }
     }
     else {
@@ -123,7 +123,7 @@ static MVMuint64 get_uint(MVMThreadContext *tc, MVMSTable *st, MVMObject *root,
         if (MP_NEG == SIGN(i))
             MVM_exception_throw_adhoc(tc, "Cannot unbox negative bigint into native unsigned integer");
         else
-            return mp_get_int64(tc, i);
+            return mp_get_int64(tc, i, 0);
     }
     else {
         return body->u.smallint.value;