diff --git a/src/caffeine/program_termination_s.f90 b/src/caffeine/program_termination_s.f90
index 68d08b90..46d7e264 100644
--- a/src/caffeine/program_termination_s.f90
+++ b/src/caffeine/program_termination_s.f90
@@ -106,13 +106,13 @@ subroutine prif_error_stop_integer(quiet, stop_code)
 
     if (present(stop_code)) then
       if (.not.quiet) then
-        write(error_unit) "ERROR STOP ", stop_code
+        write(error_unit,'(a)') "ERROR STOP ", stop_code
         flush error_unit
       end if
       exit_code = stop_code
     else
       if (.not.quiet) then
-        write(error_unit) "ERROR STOP"
+        write(error_unit,'(a)') "ERROR STOP"
         flush error_unit
       end if
       exit_code = 1_c_int