diff --git a/sys/contrib/zlib/zconf.h b/sys/contrib/zlib/zconf.h
index 3536a8c263f..283c77f93e6 100644
--- a/sys/contrib/zlib/zconf.h
+++ b/sys/contrib/zlib/zconf.h
@@ -12,6 +12,11 @@
 #ifdef _KERNEL
 #define Z_SOLO
 #endif
+#if defined(Z_SOLO)
+#include <sys/types.h>
+#define Z_U8 __uint64_t
+#define Z_U4 __uint32_t
+#endif
 #endif
 
 /*