diff --git a/library/bignum_core.c b/library/bignum_core.c
index 92a9d558a3..34223ee957 100644
--- a/library/bignum_core.c
+++ b/library/bignum_core.c
@@ -362,11 +362,6 @@ void mbedtls_mpi_core_shift_l(mbedtls_mpi_uint *X, size_t limbs,
     v0 = count / (biL);
     v1 = count & (biL - 1);
 
-    if (v0 > limbs || (v0 == limbs && v1 > 0)) {
-        memset(X, 0, limbs * ciL);
-        return;
-    }
-
     /*
      * shift by count / limb_size
      */
diff --git a/library/bignum_core.h b/library/bignum_core.h
index 2b11ccaff3..f7194982dc 100644
--- a/library/bignum_core.h
+++ b/library/bignum_core.h
@@ -297,7 +297,7 @@ void mbedtls_mpi_core_shift_r(mbedtls_mpi_uint *X, size_t limbs,
  * \brief               Shift an MPI in-place left by a number of bits.
  *
  *                      Shifting by more bits than there are bit positions
- *                      in \p X is valid and results in setting \p X to 0.
+ *                      in \p X will produce an unspecified result.
  *
  *                      This function's execution time depends on the value
  *                      of \p count (and of course \p limbs).