diff --git a/fortran/src/include/primes.f90 b/fortran/src/include/primes.f90
index 7648b2be..42afe91a 100644
--- a/fortran/src/include/primes.f90
+++ b/fortran/src/include/primes.f90
@@ -56,9 +56,7 @@ subroutine expand_sieve(potential_n)
             deallocate(prime_sieve)
         end if
         allocate(prime_sieve(new_size))
-        do i = 1, new_size
-            prime_sieve(i) = -1
-        end do
+        prime_sieve = -1
         call clear_prime_bit(0_i18t)
         call clear_prime_bit(1_i18t)
         call sieve_up_to(new_n)
diff --git a/fortran/src/include/ranges.f90 b/fortran/src/include/ranges.f90
index 3c41ad8e..93977970 100644
--- a/fortran/src/include/ranges.f90
+++ b/fortran/src/include/ranges.f90
@@ -18,6 +18,9 @@ integer function range_entry4(start, stop, step, idx) result(answer)
             length = 1 + (stop - 1 - start) / step
         elseif (step < 0 .and. start > stop) then
             length = 1 + (start - 1 - stop) / (-step)
+        else
+            answer = huge(kind(answer))  ! error
+            return
         end if
 
         if (l_idx < 0) then