diff --git a/acinclude.m4 b/acinclude.m4
index 6d34f5fa68..ea9a256863 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -1445,9 +1445,9 @@ dnl Save build info for test runner to pick up and log
 
 AC_DEFUN([CURL_PREPARE_BUILDINFO], [
   curl_pflags=""
-  case $host in
-    *-apple-*) curl_pflags="${curl_pflags} APPLE";;
-  esac
+  if test "$curl_cv_apple" = 'yes'; then
+    curl_pflags="${curl_pflags} APPLE"
+  fi
   case $host in
     *-*-*bsd*|*-*-aix*|*-*-hpux*|*-*-interix*|*-*-irix*|*-*-linux*|*-*-solaris*|*-*-sunos*|*-apple-*|*-*-cygwin*|*-*-msys*)
       curl_pflags="${curl_pflags} UNIX";;
@@ -1561,27 +1561,13 @@ dnl with very low deployment targets.
 dnl
 
 AC_DEFUN([CURL_DARWIN_CFLAGS], [
-
-  tst_cflags="no"
-  case $host in
-    *-apple-*)
-      tst_cflags="yes"
-      ;;
-  esac
-
-  AC_MSG_CHECKING([for good-to-use Darwin CFLAGS])
-  AC_MSG_RESULT([$tst_cflags]);
-
-  if test "$tst_cflags" = "yes"; then
-    old_CFLAGS=$CFLAGS
-    CFLAGS="$CFLAGS -Werror=partial-availability"
-    AC_MSG_CHECKING([whether $CC accepts -Werror=partial-availability])
-    AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
-      [AC_MSG_RESULT([yes])],
-      [AC_MSG_RESULT([no])
-      CFLAGS=$old_CFLAGS])
-  fi
-
+  old_CFLAGS=$CFLAGS
+  CFLAGS="$CFLAGS -Werror=partial-availability"
+  AC_MSG_CHECKING([whether $CC accepts -Werror=partial-availability])
+  AC_COMPILE_IFELSE([AC_LANG_PROGRAM()],
+    [AC_MSG_RESULT([yes])],
+    [AC_MSG_RESULT([no])
+    CFLAGS=$old_CFLAGS])
 ])
 
 
diff --git a/configure.ac b/configure.ac
index c975474ded..e475aa9019 100644
--- a/configure.ac
+++ b/configure.ac
@@ -596,9 +596,8 @@ case $host in
   *-apple-*) curl_cv_apple='yes';;
 esac
 
-CURL_DARWIN_CFLAGS
-
 if test "$curl_cv_apple" = 'yes'; then
+  CURL_DARWIN_CFLAGS
   CURL_SUPPORTS_BUILTIN_AVAILABLE
 fi
 
@@ -1939,51 +1938,48 @@ if test x"$want_gss" = xyes; then
     LIBS="-lgss $LIBS"
     link_pkgconfig=1
   elif test -z "$GSSAPI_LIB_DIR"; then
-    case $host in
-      *-apple-*)
-        LIBS="-lgssapi_krb5 -lresolv $LIBS"
-        ;;
-      *)
-        if test $GSSAPI_ROOT != "/usr"; then
-          CURL_CHECK_PKGCONFIG(mit-krb5-gssapi, $GSSAPI_ROOT/lib/pkgconfig)
-        else
-          CURL_CHECK_PKGCONFIG(mit-krb5-gssapi)
-        fi
-        if test -n "$host_alias" -a -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
-          dnl krb5-config doesn't have --libs-only-L or similar, put everything
-          dnl into LIBS
-          gss_libs=`$GSSAPI_ROOT/bin/$host_alias-krb5-config --libs gssapi`
-          LIBS="$gss_libs $LIBS"
-        elif test "$PKGCONFIG" != "no"; then
-          gss_libs=`$PKGCONFIG --libs mit-krb5-gssapi`
-          LIBS="$gss_libs $LIBS"
-          link_pkgconfig=1
-        elif test -f "$KRB5CONFIG"; then
-          dnl krb5-config doesn't have --libs-only-L or similar, put everything
-          dnl into LIBS
-          gss_libs=`$KRB5CONFIG --libs gssapi`
-          LIBS="$gss_libs $LIBS"
-          link_pkgconfig=1
-        else
-          case $host in
-            *-hp-hpux*)
-              gss_libname="gss"
-              ;;
-            *)
-              gss_libname="gssapi"
-              ;;
-          esac
+    if test "$curl_cv_apple" = 'yes'; then
+      LIBS="-lgssapi_krb5 -lresolv $LIBS"
+    else
+      if test $GSSAPI_ROOT != "/usr"; then
+        CURL_CHECK_PKGCONFIG(mit-krb5-gssapi, $GSSAPI_ROOT/lib/pkgconfig)
+      else
+        CURL_CHECK_PKGCONFIG(mit-krb5-gssapi)
+      fi
+      if test -n "$host_alias" -a -f "$GSSAPI_ROOT/bin/$host_alias-krb5-config"; then
+        dnl krb5-config doesn't have --libs-only-L or similar, put everything
+        dnl into LIBS
+        gss_libs=`$GSSAPI_ROOT/bin/$host_alias-krb5-config --libs gssapi`
+        LIBS="$gss_libs $LIBS"
+      elif test "$PKGCONFIG" != "no"; then
+        gss_libs=`$PKGCONFIG --libs mit-krb5-gssapi`
+        LIBS="$gss_libs $LIBS"
+        link_pkgconfig=1
+      elif test -f "$KRB5CONFIG"; then
+        dnl krb5-config doesn't have --libs-only-L or similar, put everything
+        dnl into LIBS
+        gss_libs=`$KRB5CONFIG --libs gssapi`
+        LIBS="$gss_libs $LIBS"
+        link_pkgconfig=1
+      else
+        case $host in
+          *-hp-hpux*)
+            gss_libname="gss"
+            ;;
+          *)
+            gss_libname="gssapi"
+            ;;
+        esac
 
-          if test "$GSSAPI_ROOT" != "yes"; then
-            LDFLAGS="$LDFLAGS -L$GSSAPI_ROOT/lib$libsuff"
-            LDFLAGSPC="$LDFLAGSPC -L$GSSAPI_ROOT/lib$libsuff"
-            LIBS="-l$gss_libname $LIBS"
-          else
-            LIBS="-l$gss_libname $LIBS"
-          fi
+        if test "$GSSAPI_ROOT" != "yes"; then
+          LDFLAGS="$LDFLAGS -L$GSSAPI_ROOT/lib$libsuff"
+          LDFLAGSPC="$LDFLAGSPC -L$GSSAPI_ROOT/lib$libsuff"
+          LIBS="-l$gss_libname $LIBS"
+        else
+          LIBS="-l$gss_libname $LIBS"
         fi
-        ;;
-    esac
+      fi
+    fi
   else
     LDFLAGS="$LDFLAGS $GSSAPI_LIB_DIR"
     LDFLAGSPC="$LDFLAGSPC $GSSAPI_LIB_DIR"
@@ -2738,36 +2734,34 @@ dnl Check for the presence of AppleIDN
 dnl **********************************************************************
 
 tst_links_appleidn='no'
-case $host in
-  *-apple-*)
-    AC_MSG_CHECKING([whether to build with Apple IDN])
-    OPT_IDN="default"
-    AC_ARG_WITH(apple-idn,
+if test "$curl_cv_apple" = 'yes'; then
+  AC_MSG_CHECKING([whether to build with Apple IDN])
+  OPT_IDN="default"
+  AC_ARG_WITH(apple-idn,
 AS_HELP_STRING([--with-apple-idn],[Enable AppleIDN])
 AS_HELP_STRING([--without-apple-idn],[Disable AppleIDN]),
-      [OPT_IDN=$withval])
-    case "$OPT_IDN" in
-      yes)
-        dnl --with-apple-idn option used
-        AC_MSG_RESULT([yes, check])
-        AC_CHECK_LIB(icucore, uidna_openUTS46,
-        [
-          AC_CHECK_HEADERS(unicode/uidna.h,
-            curl_idn_msg="enabled (AppleIDN)"
-            AC_DEFINE(USE_APPLE_IDN, 1, [if AppleIDN])
-            USE_APPLE_IDN=1
-            IDN_ENABLED=1
-            LIBS="-licucore -liconv $LIBS"
-            tst_links_appleidn='yes'
-          )
-        ])
-        ;;
-      *)
-        AC_MSG_RESULT([no])
-        ;;
-    esac
-    ;;
-esac
+    [OPT_IDN=$withval])
+  case "$OPT_IDN" in
+    yes)
+      dnl --with-apple-idn option used
+      AC_MSG_RESULT([yes, check])
+      AC_CHECK_LIB(icucore, uidna_openUTS46,
+      [
+        AC_CHECK_HEADERS(unicode/uidna.h,
+          curl_idn_msg="enabled (AppleIDN)"
+          AC_DEFINE(USE_APPLE_IDN, 1, [if AppleIDN])
+          USE_APPLE_IDN=1
+          IDN_ENABLED=1
+          LIBS="-licucore -liconv $LIBS"
+          tst_links_appleidn='yes'
+        )
+      ])
+      ;;
+    *)
+      AC_MSG_RESULT([no])
+      ;;
+  esac
+fi
 
 dnl **********************************************************************
 dnl Check for the presence of libidn2
@@ -4143,7 +4137,7 @@ AM_CONDITIONAL(USE_MANUAL, test x"$USE_MANUAL" = x1)
 CURL_CHECK_LIB_ARES
 CURL_CHECK_OPTION_THREADED_RESOLVER
 
-if test "$ipv6" = yes; then
+if test "$ipv6" = yes -a "$curl_cv_apple" = 'yes'; then
   CURL_DARWIN_SYSTEMCONFIGURATION
 fi
 
diff --git a/m4/curl-functions.m4 b/m4/curl-functions.m4
index bf233ff3a0..7d204ab86c 100644
--- a/m4/curl-functions.m4
+++ b/m4/curl-functions.m4
@@ -1408,11 +1408,10 @@ AC_DEFUN([CURL_CHECK_FUNC_GETADDRINFO], [
   #
   if test "$curl_cv_func_getaddrinfo" = "yes"; then
     AC_MSG_CHECKING([if getaddrinfo is threadsafe])
-    case $host in
-      *-apple-*)
-        dnl Darwin 6.0 and macOS 10.2.X and newer
-        tst_tsafe_getaddrinfo="yes"
-    esac
+    if test "$curl_cv_apple" = 'yes'; then
+      dnl Darwin 6.0 and macOS 10.2.X and newer
+      tst_tsafe_getaddrinfo="yes"
+    fi
     case $host_os in
       aix[[1234]].* | aix5.[[01]].*)
         dnl AIX 5.1 and older
@@ -4398,21 +4397,18 @@ dnl CURL_LIBRARY_PATH variable. It keeps the LD_LIBRARY_PATH
 dnl changes contained within this macro.
 
 AC_DEFUN([CURL_RUN_IFELSE], [
-  case $host in
-    *-apple-*)
-      AC_RUN_IFELSE([AC_LANG_SOURCE([$1])], $2, $3, $4)
-      ;;
-    *)
-      oldcc=$CC
-      old=$LD_LIBRARY_PATH
-      CC="sh ./run-compiler"
-      LD_LIBRARY_PATH=$CURL_LIBRARY_PATH:$old
-      export LD_LIBRARY_PATH
-      AC_RUN_IFELSE([AC_LANG_SOURCE([$1])], $2, $3, $4)
-      LD_LIBRARY_PATH=$old # restore
-      CC=$oldcc
-      ;;
-  esac
+  if test "$curl_cv_apple" = 'yes'; then
+    AC_RUN_IFELSE([AC_LANG_SOURCE([$1])], $2, $3, $4)
+  else
+    oldcc=$CC
+    old=$LD_LIBRARY_PATH
+    CC="sh ./run-compiler"
+    LD_LIBRARY_PATH=$CURL_LIBRARY_PATH:$old
+    export LD_LIBRARY_PATH
+    AC_RUN_IFELSE([AC_LANG_SOURCE([$1])], $2, $3, $4)
+    LD_LIBRARY_PATH=$old # restore
+    CC=$oldcc
+  fi
 ])
 
 dnl CURL_COVERAGE
diff --git a/m4/curl-rustls.m4 b/m4/curl-rustls.m4
index 5cd5cf1fb6..40d7af05df 100644
--- a/m4/curl-rustls.m4
+++ b/m4/curl-rustls.m4
@@ -80,17 +80,14 @@ if test "x$OPT_RUSTLS" != xno; then
         LDFLAGS="$LDFLAGS $addld"
         LDFLAGSPC="$LDFLAGSPC $addld"
         if test "$addcflags" != "-I/usr/include"; then
-            CPPFLAGS="$CPPFLAGS $addcflags"
+          CPPFLAGS="$CPPFLAGS $addcflags"
         fi
 
-        case $host in
-          *-apple-*)
-            RUSTLS_LDFLAGS="-framework Security -framework Foundation"
-            ;;
-          *)
-            RUSTLS_LDFLAGS="-lpthread -ldl -lm"
-            ;;
-        esac
+        if test "$curl_cv_apple" = 'yes'; then
+          RUSTLS_LDFLAGS="-framework Security -framework Foundation"
+        else
+          RUSTLS_LDFLAGS="-lpthread -ldl -lm"
+        fi
         AC_CHECK_LIB(rustls, rustls_connection_read,
           [
           AC_DEFINE(USE_RUSTLS, 1, [if Rustls is enabled])
diff --git a/m4/curl-sysconfig.m4 b/m4/curl-sysconfig.m4
index a0ddc0ba55..3215e7d3db 100644
--- a/m4/curl-sysconfig.m4
+++ b/m4/curl-sysconfig.m4
@@ -24,34 +24,28 @@
 
 AC_DEFUN([CURL_DARWIN_SYSTEMCONFIGURATION], [
 AC_MSG_CHECKING([whether to link macOS CoreFoundation, CoreServices, and SystemConfiguration frameworks])
-case $host in
-  *-apple-*)
-    AC_COMPILE_IFELSE([
-      AC_LANG_PROGRAM([[
-        #include <sys/types.h>
-        #include <TargetConditionals.h>
-      ]],[[
-        #if TARGET_OS_MAC && !(defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE)
-          return 0;
-        #else
-        #error Not macOS
-        #endif
-      ]])
-    ],[
-      build_for_macos="yes"
-    ],[
-      build_for_macos="no"
-    ])
-    if test "x$build_for_macos" != xno; then
-      AC_MSG_RESULT(yes)
-      SYSCONFIG_LDFLAGS='-framework CoreFoundation -framework CoreServices -framework SystemConfiguration'
-      LDFLAGS="$LDFLAGS $SYSCONFIG_LDFLAGS"
-      LDFLAGSPC="$LDFLAGSPC $SYSCONFIG_LDFLAGS"
-    else
-      AC_MSG_RESULT(no)
-    fi
-    ;;
-  *)
+  AC_COMPILE_IFELSE([
+    AC_LANG_PROGRAM([[
+      #include <sys/types.h>
+      #include <TargetConditionals.h>
+    ]],[[
+      #if TARGET_OS_MAC && !(defined(TARGET_OS_IPHONE) && TARGET_OS_IPHONE)
+        return 0;
+      #else
+      #error Not macOS
+      #endif
+    ]])
+  ],[
+    build_for_macos="yes"
+  ],[
+    build_for_macos="no"
+  ])
+  if test "x$build_for_macos" != xno; then
+    AC_MSG_RESULT(yes)
+    SYSCONFIG_LDFLAGS='-framework CoreFoundation -framework CoreServices -framework SystemConfiguration'
+    LDFLAGS="$LDFLAGS $SYSCONFIG_LDFLAGS"
+    LDFLAGSPC="$LDFLAGSPC $SYSCONFIG_LDFLAGS"
+  else
     AC_MSG_RESULT(no)
-esac
+  fi
 ])