diff --git a/js/src/jscpucfg.c b/js/src/jscpucfg.c
index 4b4ed29bd78b..da7042611f14 100644
--- a/js/src/jscpucfg.c
+++ b/js/src/jscpucfg.c
@@ -39,7 +39,7 @@
 #define INT64	long
 #endif
 #else
-#if defined(HPUX) || defined(__QNX__) || defined(SCO) || defined(UNIXWARE)
+#if defined(HPUX) || defined(__QNX__) || defined(_SCO_DS) || defined(UNIXWARE)
 #define INT64	long
 #else
 #define INT64	long long
diff --git a/js/src/jsosdep.h b/js/src/jsosdep.h
index d7071040d615..89fbaf48638e 100644
--- a/js/src/jsosdep.h
+++ b/js/src/jsosdep.h
@@ -72,7 +72,7 @@ JS_END_EXTERN_C
 #elif defined(OSF1)
 #define JS_HAVE_LONG_LONG
 
-#elif defined(SCO)
+#elif defined(_SCO_DS)
 #undef JS_HAVE_LONG_LONG
 
 #elif defined(SOLARIS)