diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 9765e2d..011816d 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -180,3 +180,4 @@ jobs:
       run: |
         set -x
         ( set +e ; fpm run  --example false-assertion  ${FPM_FLAGS} --flag "$FFLAGS" ; test $? = $ERROR_STOP_CODE )
+        ( set +e ; fpm run  --example invoke-via-macro ${FPM_FLAGS} --flag "$FFLAGS" ; test $? = $ERROR_STOP_CODE )
diff --git a/include/assert_macros.h b/include/assert_macros.h
index ba32723..ed6e390 100644
--- a/include/assert_macros.h
+++ b/include/assert_macros.h
@@ -21,8 +21,8 @@
 #endif
 
 #if ASSERTIONS
-# define call_assert(assertion) call assert_always(assertion, "call_assert(" // CPP_STRINGIFY_SOURCE(assertion) // ") in file " // __FILE__ // ", line " // fortran_stringify_integer(__LINE__))
-# define call_assert_describe(assertion, description) call assert_always(assertion, description // " in file " // __FILE__ // ", line " // fortran_stringify_integer(__LINE__))
+# define call_assert(assertion) call assert_always(assertion, "call_assert(" // CPP_STRINGIFY_SOURCE(assertion) // ")", __FILE__, __LINE__)
+# define call_assert_describe(assertion, description) call assert_always(assertion, description, __FILE__, __LINE__)
 #else
 # define call_assert(assertion)
 # define call_assert_describe(assertion, description)
diff --git a/src/assert/assert_subroutine_m.F90 b/src/assert/assert_subroutine_m.F90
index 8fd0a68..81edb3b 100644
--- a/src/assert/assert_subroutine_m.F90
+++ b/src/assert/assert_subroutine_m.F90
@@ -87,38 +87,66 @@ pure subroutine assert(assertion, description)
     
   end subroutine
 
-    pure subroutine assert_always(assertion, description)
+    pure subroutine assert_always(assertion, description, file, line)
       !! Same as above but always enforces the assertion (regardless of ASSERTIONS)
       implicit none
       logical, intent(in) :: assertion
       character(len=*), intent(in) :: description
+      character(len=*), intent(in), optional :: file
+      integer, intent(in), optional :: line
     character(len=:), allocatable :: message
+    character(len=:), allocatable :: location
     integer me
 
       check_assertion: &
       if (.not. assertion) then
+        ! Avoid harmless warnings from Cray Fortran:
+        allocate(character(len=0)::message)
+        allocate(character(len=0)::location)
+
+        ! format source location, if known
+        location = ''
+        if (present(file)) then
+          location = ' at ' // file // ':'
+          if (present(line)) then ! only print line number if file is also known
+            block
+              character(len=128) line_str
+              write(line_str, '(i0)') line
+              location = location // trim(adjustl(line_str))
+            end block
+          else
+            location = location // '<unknown>'
+          endif
+        endif
 
 #if ASSERT_MULTI_IMAGE
 #  if ASSERT_PARALLEL_CALLBACKS
-        me = assert_this_image()
+        if (associated(assert_this_image)) then
+          me = assert_this_image()
+        else
+          me = 0
+        endif
 #  else
         me = this_image()
 #  endif
    block
         character(len=128) image_number
         write(image_number, *) me
-        message = 'Assertion failure on image ' // trim(adjustl(image_number)) // ':' // description 
+        message = 'Assertion failure on image ' // trim(adjustl(image_number)) // location // ': ' // description
    end block
 #else
-        message = 'Assertion failure: ' // description
+        message = 'Assertion failure' // location // ': ' // description
         me = 0 ! avoid a harmless warning
 #endif
  
 #if ASSERT_PARALLEL_CALLBACKS
-        call assert_error_stop(message)
-#else
-        error stop message, QUIET=.false.
+        if (associated(assert_this_image)) then
+          call assert_error_stop(message)
+        else
+          ; ! deliberate fall-thru
+        endif
 #endif
+        error stop message, QUIET=.false.
 
       end if check_assertion
 
diff --git a/src/assert/fortran_stringify_integer_m.f90 b/src/assert/fortran_stringify_integer_m.f90
deleted file mode 100644
index 2f5fc92..0000000
--- a/src/assert/fortran_stringify_integer_m.f90
+++ /dev/null
@@ -1,16 +0,0 @@
-module fortran_stringify_integer_m
-  implicit none
-
-contains  
-
-  pure function fortran_stringify_integer(number) result(number_as_string)
-    integer, intent(in) :: number
-    integer, parameter :: max_len=128
-    character(len=max_len) :: untrimmed_string
-    character(len=:), allocatable :: number_as_string
-
-    write(untrimmed_string, '(i0)') number
-    number_as_string = trim(adjustl(untrimmed_string))
-  end function
-
-end module
diff --git a/src/assert_m.f90 b/src/assert_m.f90
index f9b75cb..b9a95e3 100644
--- a/src/assert_m.f90
+++ b/src/assert_m.f90
@@ -2,13 +2,5 @@ module assert_m
   !! Public interface
   use assert_subroutine_m ! DO NOT PLACE AN ONLY CLAUSE HERE! 
                           ! All public members of assert_subroutine_m are exported
-
-  ! The function below is public only to support automated
-  ! invocation via `assert_macros.h`.  For a more broadly useful
-  ! function to convert numeric data to string format, please
-  ! consider using the functions that can be accessed via the 
-  ! `string_t` generic interface in the Julienne framework at
-  ! https://go.lbl.gov/julienne.
-  use fortran_stringify_integer_m, only : fortran_stringify_integer
   implicit none
 end module