diff --git a/lib/stdint.in.h b/lib/stdint.in.h
index d20d1c7..22c2d70 100644
--- a/lib/stdint.in.h
+++ b/lib/stdint.in.h
@@ -288,12 +288,14 @@ typedef gl_uint_fast32_t gl_uint_fast16_t;
 
 /* 7.18.1.4. Integer types capable of holding object pointers */
 
+#ifndef _INTPTR_T_DECLARED
 #undef intptr_t
 #undef uintptr_t
 typedef long int gl_intptr_t;
 typedef unsigned long int gl_uintptr_t;
 #define intptr_t gl_intptr_t
 #define uintptr_t gl_uintptr_t
+#endif
 
 /* 7.18.1.5. Greatest-width integer types */