diff --git a/.github/workflows/CI-unixish.yml b/.github/workflows/CI-unixish.yml
index fafd0fb53..1d280d1db 100644
--- a/.github/workflows/CI-unixish.yml
+++ b/.github/workflows/CI-unixish.yml
@@ -314,7 +314,7 @@ jobs:
         if: contains(matrix.os, 'macos')
         run: |
           # pcre was removed from runner images in November 2022
-          brew install coreutils python3 pcre
+          brew install coreutils python3 pcre gnu-sed
 
       - name: Install missing Python packages
         run: |
@@ -335,9 +335,8 @@ jobs:
         run: |
           make -j$(nproc) check HAVE_RULES=yes
 
-      # the script uses sed parameters not supported by MacOS
+      # requires "gnu-sed" installed on macos
       - name: Run extra tests
-        if: contains(matrix.os, 'ubuntu')
         run: |
           tools/generate_and_run_more_tests.sh
 
@@ -351,9 +350,8 @@ jobs:
           cd 'cpp check/test/cli'
           python3 -m pytest test-*.py
 
-      # fails on macos since some includes (e.g. sys/epoll.h) are not available
       - name: Run cfg tests
-        if: contains(matrix.os, 'ubuntu') && matrix.os != 'ubuntu-22.04'
+        if: matrix.os != 'ubuntu-22.04'
         run: |
           make -j$(nproc) checkcfg
 
@@ -364,9 +362,7 @@ jobs:
         env:
           STRICT: 1
 
-      # it seems macos has no "wc" command
       - name: Run showtimetop5 tests
-        if: contains(matrix.os, 'ubuntu')
         run: |
           ./tools/test_showtimetop5.sh
 
diff --git a/test/cfg/gnu.c b/test/cfg/gnu.c
index 4ec584486..279c33086 100644
--- a/test/cfg/gnu.c
+++ b/test/cfg/gnu.c
@@ -19,14 +19,17 @@
 #include <sys/mman.h>
 #include <sys/sem.h>
 #include <wchar.h>
-#ifndef __CYGWIN__
+#if !defined(__CYGWIN__) && !(defined(__APPLE__) && defined(__MACH__))
 #include <sys/epoll.h>
 #endif
 #include <strings.h>
+#ifdef __gnu_linux__
 #include <error.h>
+#endif
 #include <getopt.h>
 #include <netdb.h>
 
+#ifdef __gnu_linux__
 void unreachableCode_error(void) // #11197
 {
     error(1, 0, ""); // will call exit() if the first parameter is non-zero
@@ -34,6 +37,7 @@ void unreachableCode_error(void) // #11197
     // TODO cppcheck-suppress unreachableCode
     int i;
 }
+#endif
 
 int nullPointer_gethostbyname2_r(const char* name, int af, struct hostent* ret, char* buf, size_t buflen, struct hostent** result, int* h_errnop)
 {
@@ -431,7 +435,7 @@ void leakReturnValNotUsed()
         return;
 }
 
-#ifndef __CYGWIN__
+#if !defined(__CYGWIN__) && !(defined(__APPLE__) && defined(__MACH__))
 int nullPointer_epoll_ctl(int epfd, int op, int fd, struct epoll_event *event)
 {
     // no warning is expected
diff --git a/test/cfg/posix.c b/test/cfg/posix.c
index 2544c8a0a..1dd67da21 100644
--- a/test/cfg/posix.c
+++ b/test/cfg/posix.c
@@ -7,6 +7,8 @@
 // No warnings about bad library configuration, unmatched suppressions, etc. exitcode=0
 //
 
+#define _BSD_SOURCE
+
 #include <aio.h>
 #include <stdio.h> // <- FILE
 #include <dirent.h>
@@ -19,7 +21,7 @@
 #include <pwd.h>
 #include <dlfcn.h>
 #include <fcntl.h>
-// unavailable on some linux systems #include <ndbm.h>
+// #include <ndbm.h> // unavailable on some linux systems
 #include <netdb.h>
 #include <regex.h>
 #include <time.h>
@@ -28,20 +30,23 @@
 #include <stdarg.h>
 #include <ctype.h>
 #include <stdbool.h>
+#if !(defined(__APPLE__) && defined(__MACH__))
 #include <mqueue.h>
-#define _XOPEN_SOURCE
+#endif
 #include <stdlib.h>
 #include <unistd.h>
 #include <wchar.h>
 #include <string.h>
 #include <strings.h>
 
+#if !(defined(__APPLE__) && defined(__MACH__))
 void nullPointer_mq_timedsend(mqd_t mqdes, const char* msg_ptr, size_t msg_len, unsigned msg_prio, const struct timespec* abs_timeout) {
     // cppcheck-suppress nullPointer
     (void) mq_timedsend(mqdes, NULL, msg_len, msg_prio, abs_timeout);
     // cppcheck-suppress nullPointer
     (void) mq_timedsend(mqdes, msg_ptr, msg_len, msg_prio, NULL);
 }
+#endif
 
 #if __TRACE_H__ // <trace.h>
 
@@ -143,6 +148,7 @@ int nullPointer_getopt(int argc, char* const argv[], const char* optstring)
     return getopt(argc, argv, optstring);
 }
 
+#if !(defined(__APPLE__) && defined(__MACH__))
 int invalidFunctionArgStr_mq_send(mqd_t mqdes, const char *msg_ptr, size_t msg_len, unsigned msg_prio)
 {
     // No warning is expected for:
@@ -150,6 +156,7 @@ int invalidFunctionArgStr_mq_send(mqd_t mqdes, const char *msg_ptr, size_t msg_l
     (void) mq_send(mqdes, &msg, 1, 0);
     return mq_send(mqdes, msg_ptr, msg_len, 0);
 }
+#endif
 
 void invalidFunctionArgStr_mbsnrtowcs(void)
 {
@@ -492,6 +499,7 @@ int nullPointer_aio_suspend(const struct aiocb *const aiocb_list[], int nitems,
     return aio_suspend(aiocb_list, nitems, timeout);
 }
 
+#ifdef __linux__
 // Note: Since glibc 2.28, this function symbol is no longer available to newly linked applications.
 void invalidFunctionArg_llseek(int fd, loff_t offset, int origin)
 {
@@ -522,6 +530,7 @@ void invalidFunctionArg_llseek(int fd, loff_t offset, int origin)
     // cppcheck-suppress llseekCalled
     (void)llseek(fd, offset, SEEK_END);
 }
+#endif
 
 void invalidFunctionArg_lseek64(int fd, off_t offset, int origin)
 {
diff --git a/test/cfg/runtests.sh b/test/cfg/runtests.sh
index 46833b80c..0b40098d5 100755
--- a/test/cfg/runtests.sh
+++ b/test/cfg/runtests.sh
@@ -27,9 +27,9 @@ CPPCHECK_OPT='--check-library --platform=unix64 --enable=style,information --inc
 
 # Compiler settings
 CXX=g++
-CXX_OPT='-fsyntax-only -std=c++2a -Wno-format -Wno-format-security -Wno-deprecated-declarations'
+CXX_OPT='-fsyntax-only -w -std=c++2a'
 CC=gcc
-CC_OPT='-Wno-format -Wno-stringop-overread -Wno-nonnull -Wno-implicit-function-declaration -Wno-deprecated-declarations -Wno-format-security -Wno-nonnull -fsyntax-only'
+CC_OPT='-fsyntax-only -w -std=c11'
 
 function get_pkg_config_cflags {
     set +e
@@ -194,7 +194,10 @@ function sqlite3_fn {
 
 # openmp.c
 function openmp_fn {
-    ${CC} ${CC_OPT} -fopenmp ${DIR}openmp.c
+    # MacOS compiler has no OpenMP by default
+    if ! command -v sw_vers; then
+      ${CC} ${CC_OPT} -fopenmp ${DIR}openmp.c
+    fi
 }
 
 # python.c
diff --git a/test/cfg/std.c b/test/cfg/std.c
index a3146ec75..78442a8be 100644
--- a/test/cfg/std.c
+++ b/test/cfg/std.c
@@ -28,6 +28,8 @@
 #endif
 #include <inttypes.h>
 #include <float.h>
+#include <stdarg.h>
+#include <sys/types.h>
 
 size_t invalidFunctionArgStr_wcslen(void)
 {
diff --git a/tools/run_more_tests.sh b/tools/run_more_tests.sh
index 9bc329527..86c675f90 100755
--- a/tools/run_more_tests.sh
+++ b/tools/run_more_tests.sh
@@ -1,6 +1,9 @@
 #!/bin/bash
 # Script Used by generate_and_run_more_tests.sh
 
+# "gsed" is a GNU compatible version of "sed" on MacOS
+SED_CMD=$(command -v gsed || command -v sed)
+
 DIR="$( cd "$( dirname "${BASH_SOURCE[0]}" )" && pwd )"
 
 set -e
@@ -19,85 +22,85 @@ $CPPCHECK -q --template=cppcheck1 . 2> 1.txt
 
 
 # (!x) => (x==0)
-sed  -ri 's/([(&][ ]*)\!([a-z]+)([ ]*[&)])/\1\2==0\3/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)\!([a-z]+)([ ]*[&)])/\1\2==0\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x==0) => (0==x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*0([ ]*[&)])/\10==\2\3/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*0([ ]*[&)])/\10==\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (0==x) => (!x)
-sed  -ri 's/([(&][ ]*)0[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1!\2\3/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)0[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1!\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
 
 
 # if (x) => (x!=0)
-sed  -ri 's/(if[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
+$SED_CMD -ri 's/(if[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # while (x) => (x!=0)
-sed  -ri 's/(while[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
+$SED_CMD -ri 's/(while[ ]*\([ ]*[a-z]+)([ ]*[&)])/\1!=0\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x!=0) => (0!=x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*!=[ ]*0([ ]*[&)])/\10!=\2\3/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*!=[ ]*0([ ]*[&)])/\10!=\2\3/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (0!=x) => (x)
-sed  -ri 's/([(&][ ]*)0[ ]*!=[ ]*([a-z]+[ ]*[&)])/\1\2/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)0[ ]*!=[ ]*([a-z]+[ ]*[&)])/\1\2/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
 # (x < 0) => (0 > x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*<[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x <= 0) => (0 >= x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x > 0) => (0 < x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x >= 0) => (0 <= x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*<=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x == 123) => (123 == x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*==[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (x != 123) => (123 != x)
-sed  -ri 's/([(&][ ]*)([a-z]+)[ ]*\!=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)([a-z]+)[ ]*\!=[ ]*(\-?[0-9]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
 
 # (0 < x) => (x > 0)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<[ ]*([a-z]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<[ ]*([a-z]+)([ ]*[&)])/\1\3>\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (0 <= x) => (x >= 0)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (0 > x) => (x < 0)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (0 >= x) => (x <= 0)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*<=[ ]*([a-z]+)([ ]*[&)])/\1\3>=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (123 == x) => (x == 123)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*==[ ]*([a-z]+)([ ]*[&)])/\1\3==\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 # (123 != x) => (x <= 123)
-sed  -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*\!=[ ]*([a-z]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
+$SED_CMD -ri 's/([(&][ ]*)(\-?[0-9]+)[ ]*\!=[ ]*([a-z]+)([ ]*[&)])/\1\3!=\2\4/' *.cpp
 $CPPCHECK -q --template=cppcheck1 . 2> 2.txt && diff 1.txt 2.txt
 
 
diff --git a/tools/test_showtimetop5.sh b/tools/test_showtimetop5.sh
index 99677225c..81315dd27 100755
--- a/tools/test_showtimetop5.sh
+++ b/tools/test_showtimetop5.sh
@@ -1,6 +1,8 @@
 #!/bin/bash
+# "gwc" is a GNU compatible of "wc" on MacOS
+WC_CMD=$(command -v gwc || command -v wc)
 output=$(./cppcheck --showtime=top5 cli/cmdlineparser.h --language=c++ --quiet)
 echo "$output"
-if  [[ "$(echo "$output" | wc -l)" != 7 ]] ; then
+if  [[ "$(echo "$output" | $WC_CMD -l)" != 7 ]] ; then
     false
 fi