diff --git a/src/rt/isaac/standard.h b/src/rt/isaac/standard.h
index cb6cc15b8f6..c196a37474b 100644
--- a/src/rt/isaac/standard.h
+++ b/src/rt/isaac/standard.h
@@ -13,27 +13,32 @@ Standard definitions and types, Bob Jenkins
 #  include <stddef.h>
 #  define STDDEF
 # endif
-typedef  unsigned long long  ub8;
+# ifndef STDINT
+#  include <stdint.h>
+#  define STDINT
+# endif
+
+typedef  uint64_t  ub8;
 #define UB8MAXVAL 0xffffffffffffffffLL
 #define UB8BITS 64
-typedef    signed long long  sb8;
+typedef   int64_t  sb8;
 #define SB8MAXVAL 0x7fffffffffffffffLL
-typedef  unsigned long  int  ub4;   /* unsigned 4-byte quantities */
+typedef  uint32_t  ub4;   /* unsigned 4-byte quantities */
 #define UB4MAXVAL 0xffffffff
-typedef    signed long  int  sb4;
+typedef   int32_t  sb4;
 #define UB4BITS 32
 #define SB4MAXVAL 0x7fffffff
-typedef  unsigned short int  ub2;
+typedef  uint16_t  ub2;
 #define UB2MAXVAL 0xffff
 #define UB2BITS 16
-typedef    signed short int  sb2;
+typedef   int16_t  sb2;
 #define SB2MAXVAL 0x7fff
-typedef  unsigned       char ub1;
+typedef   uint8_t  ub1;
 #define UB1MAXVAL 0xff
 #define UB1BITS 8
-typedef    signed       char sb1;   /* signed 1-byte quantities */
+typedef    int8_t  sb1;   /* signed 1-byte quantities */
 #define SB1MAXVAL 0x7f
-typedef                 int  word;  /* fastest type available */
+typedef      int  word;  /* fastest type available */
 
 #define bis(target,mask)  ((target) |=  (mask))
 #define bic(target,mask)  ((target) &= ~(mask))