diff --git a/include/monetary.h b/include/monetary.h
index 240925e87d..bddc660ce2 100644
--- a/include/monetary.h
+++ b/include/monetary.h
@@ -1,3 +1,11 @@
+/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++.  */
+#include <bits/floatn.h>
+#if defined __cplusplus && __LONG_DOUBLE_USES_FLOAT128 == 1
+# if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
+#   pragma GCC system_header
+# endif
+#endif
+
 #include <stdlib/monetary.h>
 #ifndef _ISOMAC
 #include <stdarg.h>
diff --git a/include/printf.h b/include/printf.h
index d051514119..bdcfd29f63 100644
--- a/include/printf.h
+++ b/include/printf.h
@@ -1,5 +1,13 @@
 #ifndef	_PRINTF_H
 
+/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++.  */
+#include <bits/floatn.h>
+#if defined __cplusplus && __LONG_DOUBLE_USES_FLOAT128 == 1
+# if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
+#   pragma GCC system_header
+# endif
+#endif
+
 #include <stdio-common/printf.h>
 
 # ifndef _ISOMAC
diff --git a/include/stdio.h b/include/stdio.h
index 6718af4108..1c09daf13a 100644
--- a/include/stdio.h
+++ b/include/stdio.h
@@ -2,8 +2,18 @@
 # if !defined _ISOMAC && defined _IO_MTSAFE_IO
 #  include <stdio-lock.h>
 # endif
+
+/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++.  */
+# include <bits/floatn.h>
+# if defined __cplusplus && __LONG_DOUBLE_USES_FLOAT128 == 1
+#  if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
+#    pragma GCC system_header
+#  endif
+# endif
+
 # include <libio/stdio.h>
 # ifndef _ISOMAC
+
 #  define _LIBC_STDIO_H 1
 #  include <libio/libio.h>
 
diff --git a/include/stdlib.h b/include/stdlib.h
index 926f965f69..187a41e754 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -3,6 +3,15 @@
 #ifndef _ISOMAC
 # include <stddef.h>
 #endif
+
+/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++.  */
+#include <bits/floatn.h>
+#if defined __cplusplus && __LONG_DOUBLE_USES_FLOAT128 == 1
+# if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
+#   pragma GCC system_header
+# endif
+#endif
+
 #include <stdlib/stdlib.h>
 
 /* Now define the internal interfaces.  */
diff --git a/include/wchar.h b/include/wchar.h
index 617906eb14..bb49d844be 100644
--- a/include/wchar.h
+++ b/include/wchar.h
@@ -1,4 +1,13 @@
 #ifndef _WCHAR_H
+
+/* Workaround PR90731 with GCC 9 when using ldbl redirects in C++.  */
+# include <bits/floatn.h>
+# if defined __cplusplus && __LONG_DOUBLE_USES_FLOAT128 == 1
+#  if __GNUC_PREREQ (9, 0) && !__GNUC_PREREQ (9, 3)
+#   pragma GCC system_header
+#  endif
+# endif
+
 # include <wcsmbs/wchar.h>
 # ifndef _ISOMAC