diff --git a/src/bin/pg_dump/pg_backup_archiver.h b/src/bin/pg_dump/pg_backup_archiver.h
index 91060944f1f..ef4a6903377 100644
--- a/src/bin/pg_dump/pg_backup_archiver.h
+++ b/src/bin/pg_dump/pg_backup_archiver.h
@@ -38,6 +38,16 @@
  */
 #ifdef HAVE_LIBZ
 #include <zlib.h>
+
+/*
+ * We don't use the gzgetc() macro, because zlib's configuration logic is not
+ * robust enough to guarantee that the macro will have the same ideas about
+ * struct field layout as the library itself does; see for example
+ * https://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=59711
+ * Instead, #undef the macro and fall back to the underlying function.
+ */
+#undef gzgetc
+
 #define GZCLOSE(fh) gzclose(fh)
 #define GZWRITE(p, s, n, fh) gzwrite(fh, p, (n) * (s))
 #define GZREAD(p, s, n, fh) gzread(fh, p, (n) * (s))