diff --git a/.github/workflows/windows-msvc.yml b/.github/workflows/windows-msvc.yml
index 134e7f18c..b748e62d6 100644
--- a/.github/workflows/windows-msvc.yml
+++ b/.github/workflows/windows-msvc.yml
@@ -204,6 +204,7 @@ jobs:
 
       - name: Upload testsuite-${{ matrix.arch }}-${{ matrix.target }}.log
         uses: actions/upload-artifact@v4
+        if: failure()
         with:
           name: testsuite-${{ matrix.arch }}-${{ matrix.target }}.log
           path: ${{ env.GITHUB_WORKSPACE }}/tests/testsuite.log
diff --git a/.github/workflows/windows-msys1.yml b/.github/workflows/windows-msys1.yml
index 661344910..67f3801c6 100644
--- a/.github/workflows/windows-msys1.yml
+++ b/.github/workflows/windows-msys1.yml
@@ -229,6 +229,7 @@ jobs:
 
       - name: Upload testsuite-${{ matrix.target }}.log
         uses: actions/upload-artifact@v4
+        if: failure()
         with:
           name: testsuite-${{ matrix.target }}.log
           path: ${{ env.GITHUB_WORKSPACE }}/_build/tests/testsuite.log
diff --git a/.github/workflows/windows-msys2.yml b/.github/workflows/windows-msys2.yml
index f2b5c13e9..59ba117b5 100644
--- a/.github/workflows/windows-msys2.yml
+++ b/.github/workflows/windows-msys2.yml
@@ -102,6 +102,7 @@ jobs:
 
       - name: Upload testsuite-${{matrix.sys}}-${{matrix.target}}.log
         uses: actions/upload-artifact@v4
+        if: failure()
         with:
           name: testsuite-${{matrix.sys}}-${{matrix.target}}.log
           path: ${{ env.GITHUB_WORKSPACE }}/_build/tests/testsuite.log
diff --git a/cobc/ChangeLog b/cobc/ChangeLog
index 9e21f4811..aeb1c5bf0 100644
--- a/cobc/ChangeLog
+++ b/cobc/ChangeLog
@@ -124,8 +124,6 @@
 	  of file paths. -fcopybook-deps also forces -E, -foneline-deps,
 	  -MT=copybooks, disables errors on missing copybooks and removes
 	  output on stdout.
-	* error.c (print_error_prefix): add cobc_slashify to replace backslashes
-	  by slashes, only if COB_IS_RUNNING_IN_TESTMODE is set.
         * typeck.c (check_argument_conformance): check that param is well defined
 	  to prevent a segfault
 
diff --git a/cobc/cobc.c b/cobc/cobc.c
index 0c0f3b607..36e2a6f65 100644
--- a/cobc/cobc.c
+++ b/cobc/cobc.c
@@ -9311,16 +9311,12 @@ process_file (struct filename *fn, int status)
 		}
 
 		for (l = cb_depend_list; l; l = l->next) {
-			char* filename = cobc_slashify (l->text);
-			fprintf (file, " %s%s", filename, l->next ? sep : "\n\n");
-			cobc_free (filename);
+			fprintf (file, " %s%s", l->text, l->next ? sep : "\n\n");
 		}
 		/* These lines should only be added with -MP */
 		if (cb_depend_add_phony){
 			for (l = cb_depend_list; l; l = l->next) {
-				char* filename = cobc_slashify (l->text);
-				fprintf (file, "%s:\n", filename);
-				cobc_free (filename);
+				fprintf (file, "%s:\n", l->text);
 			}
 		}
 		if (!cb_depend_file){
diff --git a/cobc/cobc.h b/cobc/cobc.h
index 4592ac21e..237c92124 100644
--- a/cobc/cobc.h
+++ b/cobc/cobc.h
@@ -672,8 +672,6 @@ DECLNORET extern void		cobc_terminate_exit (const char *, const char *) COB_A_NO
 
 extern void		cobc_set_listing_header_code (void);
 
-extern char *           cobc_slashify (const char *);
-
 /* reserved.c */
 extern struct reserved_word_list	*cobc_user_res_list;
 
diff --git a/cobc/error.c b/cobc/error.c
index cc1e24ebb..97a57cd96 100644
--- a/cobc/error.c
+++ b/cobc/error.c
@@ -62,42 +62,11 @@ size_t				cb_msg_style;
 
 DECLNORET static void		cobc_too_many_errors (void) COB_A_NORETURN;
 
-static int is_test = -1;
-
-/* Returns a copy of the argument with backslashes replaced by slashes
-in filenames, only if COB_IS_RUNNING_IN_TESTMODE. This mode simplifies
-the test of outputs, as they will be similar on Unix and Windows.
-*/
-char *
-cobc_slashify (const char *src)
-{
-	if (is_test < 0)
-		is_test = !!getenv ("COB_IS_RUNNING_IN_TESTMODE");
-
-	if (is_test){
-		int i;
-		int len = strlen (src);
-		char *dst = cobc_malloc (len+1);
-		for (i=0; i<len; i++){
-			char c = src[i];
-			if ( c == '\\' )
-				dst[i] = '/';
-			else
-				dst[i] = c;
-		}
-		dst[i] = 0;
-		return dst;
-	} else
-		return cobc_strdup (src);
-}
-
 static void
 print_error_prefix (const char *file, int line, const char *prefix)
 {
 	if (file) {
 		char *absfile = NULL ;
-		char *tmpfile = cobc_slashify (file);
-		file = tmpfile;
 		if (cb_diagnostics_absolute_paths
 		 && strcmp (file, COB_DASH) != 0
 		 && file[0] != '/'
@@ -131,7 +100,6 @@ print_error_prefix (const char *file, int line, const char *prefix)
 			fprintf (stderr, "%s:%d: ", file, line);
 		}
 		if (absfile) cobc_free (absfile);
-		cobc_free (tmpfile);
 	}
 	if (prefix) {
 		fprintf (stderr, "%s", prefix);
diff --git a/cobc/pplex.l b/cobc/pplex.l
index 8e8699c81..7a0a670e2 100644
--- a/cobc/pplex.l
+++ b/cobc/pplex.l
@@ -1288,7 +1288,7 @@ ppopen_get_file (const char *name)
 		loc.source_file = name;
 		loc.source_line = -1;
 		cb_error_x (&loc, _("recursive inclusion"));
-		return 0;		
+		return 0;
 		}
 	}
 
@@ -1299,7 +1299,7 @@ ppopen_get_file (const char *name)
 	ppin = fopen (name, "rb");
 #endif
 	if (!ppin) {
-		cb_error ("%s: %s", cobc_slashify (name), cb_get_strerror ());
+		cb_error ("%s: %s", name, cb_get_strerror ());
 		/* Note: postpone error exit as we need the saved buffers later on */
 		return 0;
 	}
@@ -1753,7 +1753,7 @@ ppcopy (const char *name, const char *lib, struct cb_replace_list *replace_list)
 				(void)access (plexbuff1, R_OK);
 				/* pass file error as we have no more places to check */
 				cb_error ("%s: %s",
-					  cobc_slashify (plexbuff1), cb_get_strerror ());
+					  plexbuff1, cb_get_strerror ());
 			}
 		}
 	}
diff --git a/tests/testsuite.src/used_binaries.at b/tests/testsuite.src/used_binaries.at
index 49c0ef157..1862b07a9 100644
--- a/tests/testsuite.src/used_binaries.at
+++ b/tests/testsuite.src/used_binaries.at
@@ -372,28 +372,13 @@ AT_DATA([prog.cob], [
            EXIT PROGRAM.
 ])
 
-AT_CHECK([TMPDIR="" TMP="notthere" TEMP="" $COMPILE prog.cob 2> compiler.output], [0], [],
-[],[
-    # On Windows, we get a failure from gcc, so the binary is not created, the stderr is mixed and exit code is 1.
-    AT_CHECK([grep libcob: compiler.output], [0], [libcob: warning: Temporary directory TMP is invalid, adjust TMPDIR!
+AT_CHECK([TMPDIR="" TMP="notthere" TEMP="" $COMPILE prog.cob], [0], [],
+[libcob: warning: Temporary directory TMP is invalid, adjust TMPDIR!
 ])
-  ],
-  [
-    AT_CHECK([cat compiler.output], [0], [libcob: warning: Temporary directory TMP is invalid, adjust TMPDIR!
-])
-    AT_CHECK([$COBCRUN_DIRECT ./prog], [0], [OK], [])
-  ])
-
-AT_CHECK([TMPDIR="" TMP="" TEMP="./prog.cob" $COMPILE prog.cob 2> compiler.output], [0], [],
-[],[
-    AT_CHECK([grep libcob: compiler.output], [0], [libcob: warning: Temporary directory TEMP is invalid, adjust TMPDIR!
-])
-  ],
-  [
-    AT_CHECK([cat compiler.output], [0], [libcob: warning: Temporary directory TEMP is invalid, adjust TMPDIR!
+AT_CHECK([$COBCRUN_DIRECT ./prog], [0], [OK], [])
+AT_CHECK([TMPDIR="" TMP="" TEMP="./prog.cob" $COMPILE prog.cob], [0], [],
+[libcob: warning: Temporary directory TEMP is invalid, adjust TMPDIR!
 ])
-  ])
-
 # TMPDIR is only checked when actually needed which is currently only the case
 # for SORT
 #AT_CHECK([TMPDIR="./prog.cob" $COBCRUN_DIRECT ./prog], [0], [OK],
@@ -1072,16 +1057,15 @@ AT_CHECK([$COBC -fdiagnostics-plain-output -fdiagnostics-show-caret -Wno-others
 ]])
 
 AT_CHECK([$COMPILE -fdiagnostics-absolute-paths -Wall prog.cob 2> compiler.output], [1])
-AT_CAPTURE_FILE([compiler.output])
 
-AT_CHECK([echo "$PWD/prog.cob:7: error: CRUD.CPY: No such file or directory" > expected.output])
-AT_CHECK([echo "$PWD/prog.cob:6: warning: numeric value is expected" >> expected.output])
-AT_CHECK([echo "$PWD/prog.cob:14: warning: ignoring redundant ." >> expected.output])
-AT_CAPTURE_FILE([expected.output])
-
-AT_CHECK([[cat compiler.output | tr '[:upper:]' '[:lower:]' | tr -d ':/\\' > compiler.output2]])
-AT_CHECK([[cat expected.output | tr '[:upper:]' '[:lower:]' | tr -d ':/\\' > expected.output2]])
-AT_CHECK([diff compiler.output2 expected.output2])
+# note: -fdiagnostics-absolute-paths will show the realpath,
+#       so for MSYS/MSVC builds that will be x:\something\prog.cob, not the output of PWD,
+#       but the _return_path function from atlocal may adjust that
+AT_CHECK([cat compiler.output | tr '\\' '/' | $SED "s|$(_return_path "$(pwd)")|DIR|"], [0],
+[DIR/prog.cob:7: error: CRUD.CPY: No such file or directory
+DIR/prog.cob:6: warning: numeric value is expected
+DIR/prog.cob:14: warning: ignoring redundant .
+], [], [echo set: $SED "s|$(_return_path "$(pwd)")|DIR|"])
 
 AT_CLEANUP
 
@@ -1091,13 +1075,13 @@ AT_SETUP([check include header file])
 
 AT_DATA([filec.h], [
 /* COB_EXT_IMPORT will be defined by libcob.h up-front */
-COB_EXT_IMPORT void rename  (const char *, const char*);
+COB_EXT_IMPORT void f (char *, long);
 ])
 AT_DATA([prog.cob], [
        IDENTIFICATION   DIVISION.
        PROGRAM-ID.      prog.
        PROCEDURE        DIVISION.
-           CALL "rename" USING "Hello".
+           CALL "f" USING "Hello".
 ])
 
 # dynamic call - program seems correct
@@ -1111,8 +1095,10 @@ AT_DATA([prog2.cob], [
        IDENTIFICATION   DIVISION.
        PROGRAM-ID.      prog.
        DATA DIVISION.
+       WORKING-STORAGE SECTION.
+       01 long USAGE BINARY-C-LONG.
        PROCEDURE        DIVISION.
-           CALL "rename" USING "Hello" "Hello2" RETURNING NOTHING.
+           CALL "f" USING "Hello" BY VALUE long RETURNING NOTHING.
 ])
 
 # note: we likely need to build an import library for some environments
@@ -1143,22 +1129,22 @@ AT_CHECK([$COMPILE_MODULE -I . --include "filec.h" -fstatic-call prog2.cob -o pr
 # * putting RETURNING NOTHING is not supported
 # * putting RETURNING OMITTED is ok, but triggers a warning (see stderr)
 
-AT_DATA([rename.copy], [
+AT_DATA([f.copy], [
        IDENTIFICATION DIVISION.
-       PROGRAM-ID. rename PROTOTYPE.
+       PROGRAM-ID. f PROTOTYPE.
        DATA DIVISION.
        LINKAGE SECTION.
        01  a PIC X(20).
-       01  b PIC X(20).
-       PROCEDURE DIVISION USING a b RETURNING OMITTED.
-       END PROGRAM rename.
+       01  b BINARY-C-LONG.
+       PROCEDURE DIVISION USING a BY VALUE b RETURNING OMITTED.
+       END PROGRAM f.
 ])
 
-AT_CHECK([$COMPILE_MODULE -Wno-unfinished --copy "rename.copy" -fstatic-call prog2.cob -o prog2c], [0], [],
+AT_CHECK([$COMPILE_MODULE -Wno-unfinished --copy "f.copy" -fstatic-call prog2.cob -o prog2c], [0], [],
 [prog2.cob:8: warning: unexpected RETURNING item
 ], [
   # Previous test "failed" --> retry with import library
-  AT_CHECK([$COMPILE_MODULE -Wno-unfinished --copy "rename.copy" -fstatic-call -L. -lfilec prog2.cob -o prog2c], [0], ignore, ignore)]
+  AT_CHECK([$COMPILE_MODULE -Wno-unfinished --copy "f.copy" -fstatic-call -L. -lfilec prog2.cob -o prog2c], [0], ignore, ignore)]
 )
 
 AT_CLEANUP
@@ -1193,7 +1179,7 @@ AT_DATA([sub/COPY3.CPY], [])
 AT_CHECK([$COMPILE_ONLY prog.cob])
 
 AT_CHECK([$COMPILE_ONLY -M prog.cob prog.cob > compiler.output], [0])
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" compiler.output], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" compiler.output], [0],
 [prog.COB_OBJECT_EXT: \
  prog.cob \
  COPY1.CPY \
@@ -1210,7 +1196,7 @@ prog.COB_OBJECT_EXT: \
 
 AT_CHECK([$COMPILE_ONLY -M -MF prog.dep prog.cob])
 
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" prog.dep], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" prog.dep], [0],
 [prog.COB_OBJECT_EXT: \
  prog.cob \
  COPY1.CPY \
@@ -1220,13 +1206,13 @@ AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" prog.dep], [0],
 ])
 
 AT_CHECK([$COMPILE_ONLY -M -fcopybook-deps prog.cob > compiler.output], [0])
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" compiler.output], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" compiler.output], [0],
 [prog.COB_OBJECT_EXT: COPY1 COPY2 sub/COPY3
 
 ])
 
 AT_CHECK([$COMPILE -g -M -MT prog.$COB_MODULE_EXT prog.cob > compiler.output], [0])
-AT_CHECK([$SED "s/prog.$COB_MODULE_EXT/prog.COB_MODULE_EXT/g" compiler.output], [0],
+AT_CHECK([$SED "s/prog.$COB_MODULE_EXT/prog.COB_MODULE_EXT/g;s/sub\\\\/sub\//g" compiler.output], [0],
 [prog.COB_MODULE_EXT: \
  prog.cob \
  COPY1.CPY \
@@ -1238,7 +1224,8 @@ AT_CHECK([$SED "s/prog.$COB_MODULE_EXT/prog.COB_MODULE_EXT/g" compiler.output],
 AT_CHECK([test -f prog.c], [1])
 AT_CHECK([test -f prog.o], [1])
 
-AT_CHECK([$COMPILE_ONLY -M -MQ '$(target)#toto' prog.cob], [0],
+AT_CHECK([$COMPILE_ONLY -M -MQ '$(target)#toto' prog.cob > compiler.output], [0])
+AT_CHECK([$SED "s/sub\\\\/sub\//g" compiler.output], [0],
 [$$(target)\#toto: \
  prog.cob \
  COPY1.CPY \
@@ -1252,7 +1239,7 @@ AT_CAPTURE_FILE([prog.d])
 
 AT_CHECK([$COMPILE -MD prog.cob])
 
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" prog.d], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" prog.d], [0],
 [prog.COB_OBJECT_EXT: \
  prog.cob \
  COPY1.CPY \
@@ -1265,7 +1252,7 @@ AT_CHECK([$COMPILE -MD -o sub/prog.exe  prog.cob])
 
 AT_CHECK([test -f sub/prog.exe])
 
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" sub/prog.d], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" sub/prog.d], [0],
 [prog.COB_OBJECT_EXT: \
  prog.cob \
  COPY1.CPY \
@@ -1276,9 +1263,7 @@ AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" sub/prog.d], [0],
 
 AT_CHECK([rm sub/COPY3.CPY])
 
-AT_CHECK([$COMPILE_ONLY -M prog.cob > compiler.output], [1], [],
-[prog.cob:12: error: sub/COPY3: No such file or directory
-])
+AT_CHECK([$COMPILE_ONLY -M prog.cob > compiler.output 2> compiler.error], [1], [], [])
 
 AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" compiler.output], [0],
 [prog.COB_OBJECT_EXT: \
@@ -1288,8 +1273,12 @@ AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" compiler.output],
 
 ])
 
+AT_CHECK([$SED "s/sub\\\\/sub\//g" compiler.error], [0],
+[prog.cob:12: error: sub/COPY3: No such file or directory
+])
+
 AT_CHECK([$COMPILE_ONLY -M -MG prog.cob > compiler.output], [0])
-AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g" compiler.output], [0],
+AT_CHECK([$SED "s/prog.$COB_OBJECT_EXT/prog.COB_OBJECT_EXT/g;s/sub\\\\/sub\//g" compiler.output], [0],
 [prog.COB_OBJECT_EXT: \
  prog.cob \
  COPY1.CPY \