diff --git a/mkspecs/android-clang/qplatformdefs.h b/mkspecs/android-clang/qplatformdefs.h
index 6f82bd0acc6..8e6905f6b19 100644
--- a/mkspecs/android-clang/qplatformdefs.h
+++ b/mkspecs/android-clang/qplatformdefs.h
@@ -116,11 +116,9 @@
         && !defined(QT_NO_READDIR64)
 #define QT_DIRENT               struct dirent64
 #define QT_READDIR              ::readdir64
-#define QT_READDIR_R            ::readdir64_r
 #else
 #define QT_DIRENT               struct dirent
 #define QT_READDIR              ::readdir
-#define QT_READDIR_R            ::readdir_r
 #endif
 
 #define QT_SOCKET_CONNECT       ::connect
diff --git a/mkspecs/common/android/qplatformdefs.h b/mkspecs/common/android/qplatformdefs.h
index 837a7952e4d..41b7315cefc 100644
--- a/mkspecs/common/android/qplatformdefs.h
+++ b/mkspecs/common/android/qplatformdefs.h
@@ -93,11 +93,9 @@
         && !defined(QT_NO_READDIR64)
 #define QT_DIRENT               struct dirent64
 #define QT_READDIR              ::readdir64
-#define QT_READDIR_R            ::readdir64_r
 #else
 #define QT_DIRENT               struct dirent
 #define QT_READDIR              ::readdir
-#define QT_READDIR_R            ::readdir_r
 #endif
 
 #define QT_SOCKET_CONNECT       ::connect
diff --git a/mkspecs/common/posix/qplatformdefs.h b/mkspecs/common/posix/qplatformdefs.h
index ffae2ac37a2..e7ce7a568db 100644
--- a/mkspecs/common/posix/qplatformdefs.h
+++ b/mkspecs/common/posix/qplatformdefs.h
@@ -108,11 +108,9 @@
         && !defined(QT_NO_READDIR64)
 #define QT_DIRENT               struct dirent64
 #define QT_READDIR              ::readdir64
-#define QT_READDIR_R            ::readdir64_r
 #else
 #define QT_DIRENT               struct dirent
 #define QT_READDIR              ::readdir
-#define QT_READDIR_R            ::readdir_r
 #endif
 
 #define QT_SOCKLEN_T            socklen_t
diff --git a/mkspecs/common/qnx/qplatformdefs.h b/mkspecs/common/qnx/qplatformdefs.h
index b608b86fbdb..285301b1577 100644
--- a/mkspecs/common/qnx/qplatformdefs.h
+++ b/mkspecs/common/qnx/qplatformdefs.h
@@ -46,11 +46,6 @@
 #define QT_NO_READDIR64
 #endif
 #include "../posix/qplatformdefs.h"
-#if defined(__EXT_QNX__READDIR64_R)
-#define QT_EXT_QNX_READDIR_R    ::_readdir64_r
-#elif defined(__EXT_QNX__READDIR_R)
-#define QT_EXT_QNX_READDIR_R    ::_readdir_r
-#endif
 
 #define QT_SNPRINTF ::snprintf
 #define QT_VSNPRINTF ::vsnprintf
diff --git a/mkspecs/common/wasm/qplatformdefs.h b/mkspecs/common/wasm/qplatformdefs.h
index 45545713df6..99087a2044a 100644
--- a/mkspecs/common/wasm/qplatformdefs.h
+++ b/mkspecs/common/wasm/qplatformdefs.h
@@ -120,11 +120,9 @@
         && !defined(QT_NO_READDIR64)
 #define QT_DIRENT               struct dirent64
 #define QT_READDIR              ::readdir64
-#define QT_READDIR_R            ::readdir64_r
 #else
 #define QT_DIRENT               struct dirent
 #define QT_READDIR              ::readdir
-#define QT_READDIR_R            ::readdir_r
 #endif
 
 #define QT_SOCKET_CONNECT       ::connect