diff --git a/libc/netbsd/resolv/res_comp.c b/libc/netbsd/resolv/res_comp.c
index 6991e8b..77b81b4 100644
--- a/libc/netbsd/resolv/res_comp.c
+++ b/libc/netbsd/resolv/res_comp.c
@@ -147,6 +147,12 @@
  * tell us anything about network-format data.  The rest of the BIND system
  * is not careful about this, but for some reason, we're doing it right here.
  */
+
+/* BIONIC: We also accept underscores in the middle of labels.
+ *         This extension is needed to make resolution on some VPN networks
+ *         work properly.
+ */
+
 #define PERIOD 0x2e
 #define	hyphenchar(c) ((c) == 0x2d)
 #define bslashchar(c) ((c) == 0x5c)
@@ -155,9 +161,10 @@
 #define alphachar(c) (((c) >= 0x41 && (c) <= 0x5a) \
 		   || ((c) >= 0x61 && (c) <= 0x7a))
 #define digitchar(c) ((c) >= 0x30 && (c) <= 0x39)
+#define underscorechar(c)  ((c) == 0x5f)
 
 #define borderchar(c) (alphachar(c) || digitchar(c))
-#define middlechar(c) (borderchar(c) || hyphenchar(c))
+#define middlechar(c) (borderchar(c) || hyphenchar(c) || underscorechar(c))
 #define	domainchar(c) ((c) > 0x20 && (c) < 0x7f)
 
 int