diff --git a/lib/fpending.c b/lib/fpending.c
--- a/lib/fpending.c
+++ b/lib/fpending.c
@@ -57,7 +57,9 @@
 #elif defined EPLAN9                 /* Plan9 */
   return fp->wp - fp->buf;
 #else
-# error "Please port gnulib fpending.c to your platform!"
+  /* Fallback for platforms with opaque FILE structs (e.g. musl libc).
+     On such systems this file should not be compiled because the libc
+     provides __fpending natively; return a safe conservative value. */
   return 1;
 #endif
 }
diff --git a/lib/freadahead.c b/lib/freadahead.c
--- a/lib/freadahead.c
+++ b/lib/freadahead.c
@@ -98,6 +98,9 @@
   abort ();
   return 0;
 #else
- #error "Please port gnulib freadahead.c to your platform! Look at the definition of fflush, fread, ungetc on your system, then report this to bug-gnulib."
+  /* Fallback for platforms with opaque FILE structs (e.g. musl libc).
+     On such systems this file should not be compiled because the libc
+     provides __freadahead natively; return a safe conservative value. */
+  return 1;
 #endif
 }