diff --git a/core/math/math-tests.factor b/core/math/math-tests.factor
index 9dcba0e6d1..fd3ad94c95 100644
--- a/core/math/math-tests.factor
+++ b/core/math/math-tests.factor
@@ -1,4 +1,4 @@
-USING: kernel math namespaces make tools.test ;
+USING: kernel layouts math math.private namespaces make tools.test ;
 IN: math.tests
 
 [ ] [ 5 [ ] times ] unit-test
@@ -96,3 +96,5 @@ IN: math.tests
 
 { t } [ 128 2^ sq 256 2^ = ] unit-test
 { t } [ 128 2^ neg sq 256 2^ = ] unit-test
+
+{ t } [ most-negative-fixnum dup >bignum bignum>fixnum-strict = ] unit-test
diff --git a/vm/bignum.cpp b/vm/bignum.cpp
index b4c1aa86c2..5b78e19d98 100644
--- a/vm/bignum.cpp
+++ b/vm/bignum.cpp
@@ -388,12 +388,28 @@ BIGNUM_TO_FOO(fixnum, fixnum, fixnum, cell)
 BIGNUM_TO_FOO(long_long, int64_t, int64_t, uint64_t)
 BIGNUM_TO_FOO(ulong_long, uint64_t, int64_t, uint64_t)
 
+bool bignum_fits_fixnum_p(bignum* bn) {
+  fixnum len = BIGNUM_LENGTH(bn);
+  if (len == 0)
+    return true;
+  if (len > 1)
+    return false;
+  bignum_digit_type dig = BIGNUM_START_PTR(bn)[0];
+  return (BIGNUM_NEGATIVE_P(bn) && dig <= -fixnum_min) ||
+      (!BIGNUM_NEGATIVE_P(bn) && dig <= fixnum_max);
+}
+
+cell bignum_maybe_to_fixnum(bignum* bn) {
+  if (bignum_fits_fixnum_p(bn))
+    return tag_fixnum(bignum_to_fixnum(bn));
+  return tag<bignum>(bn);
+}
+
 /* cannot allocate memory */
 fixnum factor_vm::bignum_to_fixnum_strict(bignum* bn) {
-  fixnum len = BIGNUM_LENGTH(bn);
-  bignum_digit_type *digits = BIGNUM_START_PTR(bn);
-  if ((len == 1 && digits[0] > fixnum_max) || (len > 1)) {
-    general_error(ERROR_OUT_OF_FIXNUM_RANGE, tag<bignum>(bn), false_object);
+
+  if (!bignum_fits_fixnum_p(bn)) {
+     general_error(ERROR_OUT_OF_FIXNUM_RANGE, tag<bignum>(bn), false_object);
   }
   fixnum fix = bignum_to_fixnum(bn);
   FACTOR_ASSERT(fix <= fixnum_max && fix >= fixnum_min);
diff --git a/vm/bignum.hpp b/vm/bignum.hpp
index 4c939fde02..fb6f063dbb 100644
--- a/vm/bignum.hpp
+++ b/vm/bignum.hpp
@@ -42,6 +42,7 @@ enum bignum_comparison {
   bignum_comparison_greater = 1
 };
 
+cell bignum_maybe_to_fixnum(bignum* bn);
 cell bignum_to_cell(bignum* bn);
 fixnum bignum_to_fixnum(bignum* bn);
 int64_t bignum_to_long_long(bignum* bn);
diff --git a/vm/math.cpp b/vm/math.cpp
index 149009790f..e46dc80b62 100644
--- a/vm/math.cpp
+++ b/vm/math.cpp
@@ -2,17 +2,6 @@
 
 namespace factor {
 
-cell bignum_maybe_to_fixnum(bignum* bn) {
-  if (BIGNUM_ZERO_P(bn))
-    return tag_fixnum(0);
-  fixnum len = BIGNUM_LENGTH(bn);
-  bignum_digit_type *digits = BIGNUM_START_PTR(bn);
-  if (len == 1 && digits[0] >= fixnum_min && digits[0] <= fixnum_max) {
-    return tag_fixnum(bignum_to_fixnum(bn));
-  }
-  return tag<bignum>(bn);
-}
-
 void factor_vm::primitive_bignum_to_fixnum() {
   ctx->replace(tag_fixnum(bignum_to_fixnum(untag<bignum>(ctx->peek()))));
 }