diff --git a/include/boost/math/special_functions/detail/bessel_i0.hpp b/include/boost/math/special_functions/detail/bessel_i0.hpp
index 5896db8f7..738a098c2 100644
--- a/include/boost/math/special_functions/detail/bessel_i0.hpp
+++ b/include/boost/math/special_functions/detail/bessel_i0.hpp
@@ -532,7 +532,9 @@ template <typename T>
 inline T bessel_i0(const T& x)
 {
    typedef mpl::int_<
-      std::numeric_limits<T>::digits == 0 ?
+      (std::numeric_limits<T>::radix != 2) ?
+      -1 :
+      (std::numeric_limits<T>::digits == 0) ?
       0 :
       std::numeric_limits<T>::digits <= 24 ?
       24 :
diff --git a/include/boost/math/special_functions/detail/bessel_i1.hpp b/include/boost/math/special_functions/detail/bessel_i1.hpp
index 0f9ba96bd..af7d1dcd9 100644
--- a/include/boost/math/special_functions/detail/bessel_i1.hpp
+++ b/include/boost/math/special_functions/detail/bessel_i1.hpp
@@ -555,6 +555,8 @@ template <typename T>
 inline T bessel_i1(const T& x)
 {
    typedef mpl::int_<
+      (std::numeric_limits<T>::radix != 2) ?
+      -1 :
       std::numeric_limits<T>::digits == 0 ?
       0 :
       std::numeric_limits<T>::digits <= 24 ?