diff -ruwN source/src/cairoint.h source-new/src/cairoint.h
--- source/src/cairoint.h	2018-08-16 19:10:53.000000000 -0600
+++ source-new/src/cairoint.h	2019-10-02 19:55:59.131388156 -0600
@@ -187,7 +187,7 @@
 static inline int cairo_const
 _cairo_popcount (uint32_t mask)
 {
-#if __GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4)
+#if !defined(__redox__) && (__GNUC__ > 3 || (__GNUC__ == 3 && __GNUC_MINOR__ >= 4))
     return __builtin_popcount (mask);
 #else
     register int y;