diff --git a/build/cmake/setup.h.in b/build/cmake/setup.h.in
index 910ab84305..b400d2eda9 100644
--- a/build/cmake/setup.h.in
+++ b/build/cmake/setup.h.in
@@ -833,12 +833,6 @@
  */
 #cmakedefine HAVE_BROKEN_LIBSTDCXX_VISIBILITY
 
-/*
- * The built-in regex supports advanced REs in additional to POSIX's basic
- * and extended. Your system regex probably won't support this, and in this
- * case WX_NO_REGEX_ADVANCED should be defined.
- */
-#cmakedefine WX_NO_REGEX_ADVANCED
 /*
  * On GNU systems use re_search instead of regexec, since the latter does a
  * strlen on the search text affecting the performance of some operations.
diff --git a/docs/doxygen/mainpages/const_cpp.h b/docs/doxygen/mainpages/const_cpp.h
index 4f321a79b5..87fbb66a24 100644
--- a/docs/doxygen/mainpages/const_cpp.h
+++ b/docs/doxygen/mainpages/const_cpp.h
@@ -201,7 +201,9 @@ Currently the following symbols exist:
         Defined if the current port supports radio menu items (see wxMenu::AppendRadioItem).}
 @itemdef{wxHAS_RAW_BITMAP, Defined if direct access to bitmap data using the classes in @c wx/rawbmp.h is supported.}
 @itemdef{wxHAS_RAW_KEY_CODES, Defined if raw key codes (see wxKeyEvent::GetRawKeyCode are supported.}
-@itemdef{wxHAS_REGEX_ADVANCED, Defined if advanced syntax is available in wxRegEx.}
+@itemdef{wxHAS_REGEX_ADVANCED, Defined if advanced syntax is available in
+    wxRegEx. This is always the case in wxWidgets 3.1.6 and later, so this
+    symbol doesn't need to be tested any more.}
 @itemdef{wxHAS_TASK_BAR_ICON, Defined if wxTaskBarIcon is available on the current platform.}
 @itemdef{wxHAS_WINDOW_LABEL_IN_STATIC_BOX, Defined if wxStaticBox::Create()
     overload taking @c wxWindow* instead of the text label is available on the current platform.}
diff --git a/include/wx/features.h b/include/wx/features.h
index 46ac758cd7..c40265ca73 100644
--- a/include/wx/features.h
+++ b/include/wx/features.h
@@ -53,13 +53,8 @@
     #undef wxHAS_CRASH_REPORT
 #endif
 
-/*  wxRE_ADVANCED is not always available, depending on regex library used
- *  (it's unavailable only if compiling via configure against system library) */
-#ifndef WX_NO_REGEX_ADVANCED
-    #define wxHAS_REGEX_ADVANCED
-#else
-    #undef wxHAS_REGEX_ADVANCED
-#endif
+/*  wxRE_ADVANCED is always defined now and kept for compatibility only. */
+#define wxHAS_REGEX_ADVANCED
 
 /* Pango-based ports and wxDFB use UTF-8 for text and font encodings
  * internally and so their fonts can handle any encodings: */
diff --git a/include/wx/osx/config_xcode.h b/include/wx/osx/config_xcode.h
index cd68ec14f8..a4be7b9df0 100644
--- a/include/wx/osx/config_xcode.h
+++ b/include/wx/osx/config_xcode.h
@@ -128,9 +128,6 @@
 #define PACKAGE_TARNAME "wxwidgets"
 #define PACKAGE_VERSION "3.1.6"
 
-// for regex
-#define WX_NO_REGEX_ADVANCED 1
-
 // for jpeg
 
 #define HAVE_STDLIB_H 1
diff --git a/include/wx/regex.h b/include/wx/regex.h
index 79676de88f..536fbc2bf2 100644
--- a/include/wx/regex.h
+++ b/include/wx/regex.h
@@ -27,10 +27,8 @@ enum
     // use extended regex syntax
     wxRE_EXTENDED = 0,
 
-    // use advanced RE syntax (built-in regex only)
-#ifdef wxHAS_REGEX_ADVANCED
+    // use advanced RE syntax (deprecated, same as wxRE_EXTENDED now)
     wxRE_ADVANCED = 1,
-#endif
 
     // use basic RE syntax
     wxRE_BASIC    = 2,
diff --git a/setup.h.in b/setup.h.in
index 895b8f2b57..9ca552a4ce 100644
--- a/setup.h.in
+++ b/setup.h.in
@@ -833,12 +833,6 @@
  */
 #undef HAVE_BROKEN_LIBSTDCXX_VISIBILITY
 
-/*
- * The built-in regex supports advanced REs in additional to POSIX's basic
- * and extended. Your system regex probably won't support this, and in this
- * case WX_NO_REGEX_ADVANCED should be defined.
- */
-#undef WX_NO_REGEX_ADVANCED
 /*
  * On GNU systems use re_search instead of regexec, since the latter does a
  * strlen on the search text affecting the performance of some operations.
diff --git a/setup.h_vms b/setup.h_vms
index 249b27cd47..261a3ea2c6 100644
--- a/setup.h_vms
+++ b/setup.h_vms
@@ -901,12 +901,6 @@ typedef pid_t GPid;
  */
 #undef HAVE_BROKEN_LIBSTDCXX_VISIBILITY
 
-/*
- * The built-in regex supports advanced REs in additional to POSIX's basic
- * and extended. Your system regex probably won't support this, and in this
- * case WX_NO_REGEX_ADVANCED should be defined.
- */
-#undef WX_NO_REGEX_ADVANCED
 /*
  * On GNU systems use re_search instead of regexec, since the latter does a
  * strlen on the search text affecting the performance of some operations.
diff --git a/tests/regex/regextest.cpp b/tests/regex/regextest.cpp
index 1178341c95..b7cd1b1817 100644
--- a/tests/regex/regextest.cpp
+++ b/tests/regex/regextest.cpp
@@ -40,11 +40,6 @@
 #endif
 
 
-// many of the tests are specific to the builtin regex lib, so only attempts
-// to do them when using the builtin regex lib.
-//
-#ifdef wxHAS_REGEX_ADVANCED
-
 #include "wx/regex.h"
 #include <string>
 #include <vector>
@@ -347,10 +342,8 @@ void RegExTestCase::runTest()
         doTest(wxRE_BASIC);
     if (m_extended)
         doTest(wxRE_EXTENDED);
-#ifdef wxHAS_REGEX_ADVANCED
     if (m_advanced || (!m_basic && !m_extended))
         doTest(wxRE_ADVANCED);
-#endif
 }
 
 // Try the test for a single flavour of expression
@@ -492,6 +485,4 @@ CheckRE(
 #include "regex.inc"
 
 
-#endif // wxHAS_REGEX_ADVANCED
-
 #endif // wxUSE_REGEX
diff --git a/tests/regex/wxregextest.cpp b/tests/regex/wxregextest.cpp
index db0ab088cc..4bc6463f06 100644
--- a/tests/regex/wxregextest.cpp
+++ b/tests/regex/wxregextest.cpp
@@ -184,8 +184,6 @@ TEST_CASE("wxRegEx::ConvertFromBasic", "[regex][basic]")
     CHECK( wxRegEx::ConvertFromBasic("[^$\\)]") == "[^$\\)]" );
 }
 
-#ifdef wxHAS_REGEX_ADVANCED
-
 TEST_CASE("wxRegEx::Unicode", "[regex][unicode]")
 {
     const wxString cyrillicCapitalA(L"\u0410");
@@ -198,6 +196,4 @@ TEST_CASE("wxRegEx::Unicode", "[regex][unicode]")
     CHECK( re.GetMatch(cyrillicSmallA) == cyrillicSmallA );
 }
 
-#endif // wxHAS_REGEX_ADVANCED
-
 #endif // wxUSE_REGEX