diff --git a/nsprpub/pr/include/md/_linux.cfg b/nsprpub/pr/include/md/_linux.cfg
index 465c64ea29ff..776c21e0fc79 100644
--- a/nsprpub/pr/include/md/_linux.cfg
+++ b/nsprpub/pr/include/md/_linux.cfg
@@ -48,7 +48,53 @@
 
 #define PR_AF_INET6 10  /* same as AF_INET6 */
 
-#ifdef __powerpc__
+#ifdef __powerpc64__
+
+#undef  IS_LITTLE_ENDIAN
+#define IS_BIG_ENDIAN    1
+#define IS_64
+
+#define PR_BYTES_PER_BYTE   1
+#define PR_BYTES_PER_SHORT  2
+#define PR_BYTES_PER_INT    4
+#define PR_BYTES_PER_INT64  8
+#define PR_BYTES_PER_LONG   8
+#define PR_BYTES_PER_FLOAT  4
+#define PR_BYTES_PER_DOUBLE 8
+#define PR_BYTES_PER_WORD   8
+#define PR_BYTES_PER_DWORD  8
+
+#define PR_BITS_PER_BYTE    8
+#define PR_BITS_PER_SHORT   16
+#define PR_BITS_PER_INT     32
+#define PR_BITS_PER_INT64   64
+#define PR_BITS_PER_LONG    64
+#define PR_BITS_PER_FLOAT   32
+#define PR_BITS_PER_DOUBLE  64
+#define PR_BITS_PER_WORD    64
+
+#define PR_BITS_PER_BYTE_LOG2   3
+#define PR_BITS_PER_SHORT_LOG2  4
+#define PR_BITS_PER_INT_LOG2    5
+#define PR_BITS_PER_INT64_LOG2  6
+#define PR_BITS_PER_LONG_LOG2   6
+#define PR_BITS_PER_FLOAT_LOG2  5
+#define PR_BITS_PER_DOUBLE_LOG2 6
+#define PR_BITS_PER_WORD_LOG2   6
+
+#define PR_ALIGN_OF_SHORT   2
+#define PR_ALIGN_OF_INT     4
+#define PR_ALIGN_OF_LONG    8
+#define PR_ALIGN_OF_INT64   8
+#define PR_ALIGN_OF_FLOAT   4
+#define PR_ALIGN_OF_DOUBLE  8
+#define PR_ALIGN_OF_POINTER 8
+#define PR_ALIGN_OF_WORD    8
+
+#define PR_BYTES_PER_WORD_LOG2   3
+#define PR_BYTES_PER_DWORD_LOG2  3
+
+#elif defined(__powerpc__)
 
 #undef  IS_LITTLE_ENDIAN
 #define IS_BIG_ENDIAN    1
diff --git a/nsprpub/pr/include/md/_linux.h b/nsprpub/pr/include/md/_linux.h
index 96e8f1c3a40d..92a5f38aa6f8 100644
--- a/nsprpub/pr/include/md/_linux.h
+++ b/nsprpub/pr/include/md/_linux.h
@@ -46,7 +46,9 @@
 
 #define PR_LINKER_ARCH	"linux"
 #define _PR_SI_SYSNAME  "LINUX"
-#ifdef __powerpc__
+#ifdef __powerpc64__
+#define _PR_SI_ARCHITECTURE "ppc64"
+#elif defined(__powerpc__)
 #define _PR_SI_ARCHITECTURE "ppc"
 #elif defined(__alpha)
 #define _PR_SI_ARCHITECTURE "alpha"