diff --git a/libgcc/config/rs6000/_sprintfkf.c b/libgcc/config/rs6000/_sprintfkf.c
index a7fdfb483c9..2d624f14e25 100644
--- a/libgcc/config/rs6000/_sprintfkf.c
+++ b/libgcc/config/rs6000/_sprintfkf.c
@@ -28,6 +28,7 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include <soft-fp.h>
 #include <quad-float128.h>
 #include <stdio.h>
+#include <_sprintfkf.h>
 
 /* This function must be built with IBM 128-bit as long double, so that we can
    access the strfroml function if do not have an IEEE 128-bit version, and if
diff --git a/libgcc/config/rs6000/_sprintfkf.h b/libgcc/config/rs6000/_sprintfkf.h
index 637d104c882..de9d7137f69 100644
--- a/libgcc/config/rs6000/_sprintfkf.h
+++ b/libgcc/config/rs6000/_sprintfkf.h
@@ -24,5 +24,4 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 /* Declaration of the conversion function to IEEE 128-bit floating point from
    string using snprintf.  */
 
-extern int __sprintfkf (char *restrict, const char *restrict, ...);
-
+extern int __sprintfkf (char *restrict, const char *restrict, _Float128);