diff --git a/lib/Math/BigInt/LTM.pm b/lib/Math/BigInt/LTM.pm
index 4ee7bb7..dfe6b67 100644
--- a/lib/Math/BigInt/LTM.pm
+++ b/lib/Math/BigInt/LTM.pm
@@ -331,7 +331,7 @@
     0 + $class -> _str($x);
 }
 
-### same as _fac() in Math::BigInt::Lib
+### PATCHED _fac() from Math::BigInt::Lib
 sub _fac {
     # factorial
     my ($class, $x) = @_;
@@ -339,7 +339,9 @@
     my $two = $class -> _two();
 
     if ($class -> _acmp($x, $two) < 0) {
-        return $class -> _one();
+        ###HACK: needed for MBI 1.999715 compatibility
+        ###return $class -> _one();
+        $class->_set($x, 1); return $x
     }
 
     my $i = $class -> _copy($x);
@@ -351,7 +353,7 @@
     return $x;
 }
 
-### same as _dfac() in Math::BigInt::Lib
+### PATCHED _dfac() from Math::BigInt::Lib
 sub _dfac {
     # double factorial
     my ($class, $x) = @_;
@@ -359,7 +361,9 @@
     my $two = $class -> _two();
 
     if ($class -> _acmp($x, $two) < 0) {
-        return $class -> _one();
+        ###HACK: needed for MBI 1.999715 compatibility
+        ###return $class -> _one();
+        $class->_set($x, 1); return $x
     }
 
     my $i = $class -> _copy($x);