diff --git a/js/src/configure.in b/js/src/configure.in
index 17fded10717d..ceef221347b2 100644
--- a/js/src/configure.in
+++ b/js/src/configure.in
@@ -1596,6 +1596,7 @@ case "$target" in
     if test "$COMPILE_ENVIRONMENT"; then
         AC_CHECK_HEADERS(sys/inttypes.h)
     fi
+    AC_DEFINE(JS_SYS_TYPES_H_DEFINES_EXACT_SIZE_TYPES)
     AC_DEFINE(NSCAP_DISABLE_DEBUG_PTR_TYPES)
     ;;
 
diff --git a/js/src/js-config.h.in b/js/src/js-config.h.in
index 5e667e31064e..7555d933f268 100644
--- a/js/src/js-config.h.in
+++ b/js/src/js-config.h.in
@@ -56,6 +56,9 @@
    useable.  See jstypes.h and jsstdint.h.  */
 #undef JS_HAVE_STDINT_H
 
+/* Define to 1 if the <sys/types.h> defines int8_t, etc. */
+#undef JS_SYS_TYPES_H_DEFINES_EXACT_SIZE_TYPES
+
 /* Define to 1 if the N-byte __intN types are defined by the
    compiler.  */
 #undef JS_HAVE___INTN
diff --git a/js/src/jsinttypes.h b/js/src/jsinttypes.h
index 7e06b3edf0d5..5f90eaaf7c0e 100644
--- a/js/src/jsinttypes.h
+++ b/js/src/jsinttypes.h
@@ -67,9 +67,14 @@
  * <stdint.h> itself is available.
  */
 
-#if defined(JS_HAVE_STDINT_H)
+#if defined(JS_HAVE_STDINT_H) || \
+    defined(JS_SYS_TYPES_H_DEFINES_EXACT_SIZE_TYPES)
 
+#if defined(JS_HAVE_STDINT_H)
 #include <stdint.h>
+#else
+#include <sys/types.h>
+#endif
 
 typedef int8_t   JSInt8;
 typedef int16_t  JSInt16;
diff --git a/js/src/jsstdint.h b/js/src/jsstdint.h
index 4ced93e9c108..446a87319ac0 100644
--- a/js/src/jsstdint.h
+++ b/js/src/jsstdint.h
@@ -58,7 +58,8 @@
 /* If we have a working stdint.h, then jsinttypes.h has already
    defined the standard integer types.  Otherwise, define the standard
    names in terms of the 'JS' types.  */
-#if ! defined(JS_HAVE_STDINT_H)
+#if ! defined(JS_HAVE_STDINT_H) && \
+    ! defined(JS_SYS_TYPES_H_DEFINES_EXACT_SIZE_TYPES)
 
 typedef JSInt8  int8_t;
 typedef JSInt16 int16_t;