diff --git a/lib/libc/alpha/_fpmath.h b/lib/libc/alpha/_fpmath.h
index e0df30f3bb3..1f3e525e2d9 100644
--- a/lib/libc/alpha/_fpmath.h
+++ b/lib/libc/alpha/_fpmath.h
@@ -39,6 +39,9 @@ union IEEEl2bits {
 #define	mask_nbit_l(u)	((void)0)
 #define	LDBL_IMPLICIT_NBIT
 
+#define	LDBL_MANH_SIZE	20
+#define	LDBL_MANL_SIZE	32
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)(u).bits.manh;		\
diff --git a/lib/libc/amd64/_fpmath.h b/lib/libc/amd64/_fpmath.h
index d8b60f2238e..e3645186aff 100644
--- a/lib/libc/amd64/_fpmath.h
+++ b/lib/libc/amd64/_fpmath.h
@@ -40,6 +40,9 @@ union IEEEl2bits {
 
 #define	mask_nbit_l(u)	((u).bits.manh &= 0x7fffffff)
 
+#define	LDBL_MANH_SIZE	32
+#define	LDBL_MANL_SIZE	32
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)(u).bits.manh;		\
diff --git a/lib/libc/i386/_fpmath.h b/lib/libc/i386/_fpmath.h
index 35fe3768ba6..e5347946fd7 100644
--- a/lib/libc/i386/_fpmath.h
+++ b/lib/libc/i386/_fpmath.h
@@ -39,6 +39,9 @@ union IEEEl2bits {
 
 #define	mask_nbit_l(u)	((u).bits.manh &= 0x7fffffff)
 
+#define	LDBL_MANH_SIZE	32
+#define	LDBL_MANL_SIZE	32
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)(u).bits.manh;		\
diff --git a/lib/libc/ia64/_fpmath.h b/lib/libc/ia64/_fpmath.h
index 5d7a36b29e5..311574a973d 100644
--- a/lib/libc/ia64/_fpmath.h
+++ b/lib/libc/ia64/_fpmath.h
@@ -54,6 +54,9 @@ union IEEEl2bits {
 #define	mask_nbit_l(u)	((u).bits.manh &= 0xffffff7f)
 #endif
 
+#define	LDBL_MANH_SIZE	32
+#define	LDBL_MANL_SIZE	32
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)(u).bits.manh;		\
diff --git a/lib/libc/powerpc/_fpmath.h b/lib/libc/powerpc/_fpmath.h
index 32a3e048700..9672da30f32 100644
--- a/lib/libc/powerpc/_fpmath.h
+++ b/lib/libc/powerpc/_fpmath.h
@@ -39,6 +39,9 @@ union IEEEl2bits {
 #define	mask_nbit_l(u)	((void)0)
 #define	LDBL_IMPLICIT_NBIT
 
+#define	LDBL_MANH_SIZE	48
+#define	LDBL_MANL_SIZE	64
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)((u).bits.manl >> 32);      	\
diff --git a/lib/libc/sparc64/_fpmath.h b/lib/libc/sparc64/_fpmath.h
index 69a4b032eeb..ba8c403af08 100644
--- a/lib/libc/sparc64/_fpmath.h
+++ b/lib/libc/sparc64/_fpmath.h
@@ -40,6 +40,9 @@ union IEEEl2bits {
 #define	mask_nbit_l(u)	((void)0)
 #define	LDBL_IMPLICIT_NBIT
 
+#define	LDBL_MANH_SIZE	48
+#define	LDBL_MANL_SIZE	64
+
 #define	LDBL_TO_ARRAY32(u, a) do {			\
 	(a)[0] = (uint32_t)(u).bits.manl;		\
 	(a)[1] = (uint32_t)((u).bits.manl >> 32);      	\