diff --git a/cmake.config/CMakeLists.txt b/cmake.config/CMakeLists.txt
index 1a06eccf68..7e8c7ecd16 100644
--- a/cmake.config/CMakeLists.txt
+++ b/cmake.config/CMakeLists.txt
@@ -28,9 +28,7 @@ int main(void)
 check_type_size("int" SIZEOF_INT LANGUAGE C)
 check_type_size("long" SIZEOF_LONG LANGUAGE C)
 check_type_size("intmax_t" SIZEOF_INTMAX_T LANGUAGE C)
-check_type_size("int32_t" SIZEOF_INT32_T LANGUAGE C)
 check_type_size("size_t" SIZEOF_SIZE_T LANGUAGE C)
-check_type_size("long long" SIZEOF_LONG_LONG LANGUAGE C)
 check_type_size("void *" SIZEOF_VOID_PTR LANGUAGE C)
 
 check_symbol_exists(_NSGetEnviron crt_externs.h HAVE__NSGETENVIRON)
@@ -38,7 +36,6 @@ check_symbol_exists(_NSGetEnviron crt_externs.h HAVE__NSGETENVIRON)
 # Headers
 check_include_files(langinfo.h HAVE_LANGINFO_H)
 check_include_files(locale.h HAVE_LOCALE_H)
-check_include_files(pwd.h HAVE_PWD_H)
 check_include_files(strings.h HAVE_STRINGS_H)
 check_include_files(sys/utsname.h HAVE_SYS_UTSNAME_H)
 check_include_files(termios.h HAVE_TERMIOS_H)
@@ -47,15 +44,8 @@ check_include_files(sys/sdt.h HAVE_SYS_SDT_H)
 
 # Functions
 check_function_exists(fseeko HAVE_FSEEKO)
-check_function_exists(getpwent HAVE_GETPWENT)
-check_function_exists(getpwnam HAVE_GETPWNAM)
-check_function_exists(getpwuid HAVE_GETPWUID)
 check_function_exists(readv HAVE_READV)
-check_function_exists(opendir HAVE_OPENDIR)
 check_function_exists(readlink HAVE_READLINK)
-check_function_exists(setpgid HAVE_SETPGID)
-check_function_exists(setsid HAVE_SETSID)
-check_function_exists(sigaction HAVE_SIGACTION)
 check_function_exists(strnlen HAVE_STRNLEN)
 check_function_exists(strcasecmp HAVE_STRCASECMP)
 check_function_exists(strncasecmp HAVE_STRNCASECMP)
@@ -64,22 +54,28 @@ check_function_exists(strptime HAVE_STRPTIME)
 check_c_source_compiles("
 #include <sys/types.h>
 #include <dirent.h>
+#include <sys/file.h>
 int main(void)
 {
   DIR *dir = opendir(\"dirname\");
   dirfd(dir);
-  return 0;
-}
-" HAVE_DIRFD)
-
-check_c_source_compiles("
-#include <sys/file.h>
-int main(void)
-{
   flock(10, LOCK_SH);
   return 0;
 }
-" HAVE_FLOCK)
+" HAVE_DIRFD_AND_FLOCK)
+
+
+check_c_source_compiles("
+#include <pwd.h>
+int main(void)
+{
+  getpwent();
+  getpwuid(0);
+  getpwnam(\"root\");
+  return 0;
+}
+" HAVE_PWD_FUNCS)
+
 
 if(CMAKE_SYSTEM_NAME STREQUAL "SunOS")
   check_c_source_compiles("
@@ -101,11 +97,13 @@ if(HAVE_LANGINFO_H)
 endif()
 
 check_include_files("endian.h" HAVE_ENDIAN_H)
-check_include_files("sys/endian.h" HAVE_SYS_ENDIAN_H)
 
 set(ENDIAN_INCLUDE_FILE "endian.h")
-if(HAVE_SYS_ENDIAN_H AND NOT HAVE_ENDIAN_H)
-  set(ENDIAN_INCLUDE_FILE "sys/endian.h")
+if(NOT HAVE_ENDIAN_H)
+  check_include_files("sys/endian.h" HAVE_SYS_ENDIAN_H)
+  if (HAVE_SYS_ENDIAN_H)
+    set(ENDIAN_INCLUDE_FILE "sys/endian.h")
+  endif()
 endif()
 
 set(SI "#include <stdint.h>\n")
diff --git a/cmake.config/config.h.in b/cmake.config/config.h.in
index 4669e42c0f..a1b46f8cb5 100644
--- a/cmake.config/config.h.in
+++ b/cmake.config/config.h.in
@@ -3,9 +3,7 @@
 
 #cmakedefine SIZEOF_INT @SIZEOF_INT@
 #cmakedefine SIZEOF_INTMAX_T @SIZEOF_INTMAX_T@
-#cmakedefine SIZEOF_INT32_T @SIZEOF_INT32_T@
 #cmakedefine SIZEOF_LONG @SIZEOF_LONG@
-#cmakedefine SIZEOF_LONG_LONG @SIZEOF_LONG_LONG@
 #cmakedefine SIZEOF_SIZE_T @SIZEOF_SIZE_T@
 
 #if @SIZEOF_VOID_PTR@ == 8
@@ -19,18 +17,12 @@
 #cmakedefine HAVE__NSGETENVIRON
 #cmakedefine HAVE_FD_CLOEXEC
 #cmakedefine HAVE_FSEEKO
-#cmakedefine HAVE_GETPWENT
-#cmakedefine HAVE_GETPWNAM
-#cmakedefine HAVE_GETPWUID
 #cmakedefine HAVE_LANGINFO_H
 #cmakedefine HAVE_LOCALE_H
 #cmakedefine HAVE_NL_LANGINFO_CODESET
 #cmakedefine HAVE_NL_MSG_CAT_CNTR
-#cmakedefine HAVE_PWD_H
+#cmakedefine HAVE_PWD_FUNCS
 #cmakedefine HAVE_READLINK
-#cmakedefine HAVE_SETPGID
-#cmakedefine HAVE_SETSID
-#cmakedefine HAVE_SIGACTION
 #cmakedefine HAVE_STRNLEN
 #cmakedefine HAVE_STRCASECMP
 #cmakedefine HAVE_STRINGS_H
@@ -51,8 +43,7 @@
 #  undef HAVE_SYS_UIO_H
 # endif
 #endif
-#cmakedefine HAVE_DIRFD
-#cmakedefine HAVE_FLOCK
+#cmakedefine HAVE_DIRFD_AND_FLOCK
 #cmakedefine HAVE_FORKPTY
 
 #ifndef UNIT_TESTING
diff --git a/src/nvim/CMakeLists.txt b/src/nvim/CMakeLists.txt
index 8c23b501f9..504dde5a9c 100755
--- a/src/nvim/CMakeLists.txt
+++ b/src/nvim/CMakeLists.txt
@@ -240,13 +240,15 @@ endif()
 if(UNIX)
   # -fstack-protector breaks non Unix builds even in Mingw-w64
   check_c_compiler_flag(-fstack-protector-strong HAS_FSTACK_PROTECTOR_STRONG_FLAG)
-  check_c_compiler_flag(-fstack-protector HAS_FSTACK_PROTECTOR_FLAG)
   if(HAS_FSTACK_PROTECTOR_STRONG_FLAG)
     target_compile_options(main_lib INTERFACE -fstack-protector-strong)
     target_link_libraries(main_lib INTERFACE -fstack-protector-strong)
-  elseif(HAS_FSTACK_PROTECTOR_FLAG)
-    target_compile_options(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
-    target_link_libraries(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+  else()
+    check_c_compiler_flag(-fstack-protector HAS_FSTACK_PROTECTOR_FLAG)
+    if(HAS_FSTACK_PROTECTOR_FLAG)
+      target_compile_options(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+      target_link_libraries(main_lib INTERFACE -fstack-protector --param ssp-buffer-size=4)
+    endif()
   endif()
 endif()
 
diff --git a/src/nvim/charset.c b/src/nvim/charset.c
index 1cfb5350f3..bf18d110c0 100644
--- a/src/nvim/charset.c
+++ b/src/nvim/charset.c
@@ -1446,7 +1446,7 @@ long getdigits_long(char **pp, bool strict, long def)
 int32_t getdigits_int32(char **pp, bool strict, long def)
 {
   intmax_t number = getdigits(pp, strict, def);
-#if SIZEOF_INTMAX_T > SIZEOF_INT32_T
+#if SIZEOF_INTMAX_T > 4
   if (strict) {
     assert(number >= INT32_MIN && number <= INT32_MAX);
   } else if (!(number >= INT32_MIN && number <= INT32_MAX)) {
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index 755b8e0834..c93df43cff 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -68,7 +68,7 @@
 # include "nvim/charset.h"
 #endif
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 # include <dirent.h>
 # include <sys/file.h>
 #endif
@@ -5146,7 +5146,7 @@ void forward_slash(char *fname)
 
 /// Path to Nvim's own temp dir. Ends in a slash.
 static char *vim_tempdir = NULL;
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 DIR *vim_tempdir_dp = NULL;  ///< File descriptor of temp dir
 #endif
 
@@ -5316,7 +5316,7 @@ int delete_recursive(const char *name)
   return result;
 }
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
 /// Open temporary directory and take file lock to prevent
 /// to be auto-cleaned.
 static void vim_opentempdir(void)
@@ -5353,7 +5353,7 @@ void vim_deltempdir(void)
     return;
   }
 
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
   vim_closetempdir();
 #endif
   // remove the trailing path separator
@@ -5391,7 +5391,7 @@ static bool vim_settempdir(char *tempdir)
   vim_FullName(tempdir, buf, MAXPATHL, false);
   add_pathsep(buf);
   vim_tempdir = xstrdup(buf);
-#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+#ifdef HAVE_DIRFD_AND_FLOCK
   vim_opentempdir();
 #endif
   xfree(buf);
diff --git a/src/nvim/os/os_defs.h b/src/nvim/os/os_defs.h
index f86c0d3483..9e201f1dfa 100644
--- a/src/nvim/os/os_defs.h
+++ b/src/nvim/os/os_defs.h
@@ -36,10 +36,9 @@
 // Command-processing buffer. Use large buffers for all platforms.
 #define CMDBUFFSIZE 1024
 
-// Note: Some systems need both string.h and strings.h (Savage).  However,
-// some systems can't handle both, only use string.h in that case.
+// Note: Some systems need both string.h and strings.h (Savage).
 #include <string.h>
-#if defined(HAVE_STRINGS_H) && !defined(NO_STRINGS_WITH_STRING_H)
+#ifdef HAVE_STRINGS_H
 # include <strings.h>
 #endif
 
diff --git a/src/nvim/os/shell.c b/src/nvim/os/shell.c
index f1e2c5440f..f7d1154169 100644
--- a/src/nvim/os/shell.c
+++ b/src/nvim/os/shell.c
@@ -399,8 +399,8 @@ int os_expand_wildcards(int num_pat, char **pat, int *num_file, char ***file, in
     fclose(fd);
     return FAIL;
   }
-#if SIZEOF_LONG_LONG > SIZEOF_SIZE_T
-  assert(templen <= (long long)SIZE_MAX);  // NOLINT(runtime/int)
+#if 8 > SIZEOF_SIZE_T
+  assert(templen <= SIZE_MAX);  // NOLINT(runtime/int)
 #endif
   len = (size_t)templen;
   fseek(fd, 0L, SEEK_SET);
diff --git a/src/nvim/os/users.c b/src/nvim/os/users.c
index ef2986246b..411ba91fa7 100644
--- a/src/nvim/os/users.c
+++ b/src/nvim/os/users.c
@@ -15,7 +15,7 @@
 #include "nvim/os/os.h"
 #include "nvim/types.h"
 #include "nvim/vim.h"
-#ifdef HAVE_PWD_H
+#ifdef HAVE_PWD_FUNCS
 # include <pwd.h>
 #endif
 #ifdef MSWIN
@@ -50,7 +50,7 @@ int os_get_usernames(garray_T *users)
   }
   ga_init(users, sizeof(char *), 20);
 
-#if defined(HAVE_GETPWENT) && defined(HAVE_PWD_H)
+#ifdef HAVE_PWD_FUNCS
   {
     struct passwd *pw;
 
@@ -81,7 +81,7 @@ int os_get_usernames(garray_T *users)
     }
   }
 #endif
-#if defined(HAVE_GETPWNAM)
+#ifdef HAVE_PWD_FUNCS
   {
     const char *user_env = os_getenv("USER");
 
@@ -141,7 +141,7 @@ int os_get_username(char *s, size_t len)
 /// @return OK if a username was found, else FAIL.
 int os_get_uname(uv_uid_t uid, char *s, size_t len)
 {
-#if defined(HAVE_PWD_H) && defined(HAVE_GETPWUID)
+#ifdef HAVE_PWD_FUNCS
   struct passwd *pw;
 
   if ((pw = getpwuid(uid)) != NULL  // NOLINT(runtime/threadsafe_fn)
@@ -159,7 +159,7 @@ int os_get_uname(uv_uid_t uid, char *s, size_t len)
 /// Caller must free() the returned string.
 char *os_get_userdir(const char *name)
 {
-#if defined(HAVE_GETPWNAM) && defined(HAVE_PWD_H)
+#ifdef HAVE_PWD_FUNCS
   if (name == NULL || *name == NUL) {
     return NULL;
   }