X-Git-Url: https://git.exim.org/exim.git/blobdiff_plain/b87a6e0eedc31fdaa0d468349769b265db904aa7..4789da3a20432b8ce9cdccfb0713c027f91447c9:/src/src/exim.h

diff --git a/src/src/exim.h b/src/src/exim.h
index 987aebf83..32871660d 100644
--- a/src/src/exim.h
+++ b/src/src/exim.h
@@ -21,9 +21,11 @@ This call dates back at least as far as SUSv2. */
 #define HAVE_SRANDOM
 
 /* This is primarily for the Gnu C library; we define it before os.h so that
-os.h has a chance to hurriedly undef it, Just In Case. */
+os.h has a chance to hurriedly undef it, Just In Case.  We need C99 for some
+64-bit math support, and defining _ISOC99_SOURCE breaks <resolv.h> and friends.
+*/
 
-#define _ISOC99_SOURCE 1
+#define _GNU_SOURCE 1
 
 /* First of all include the os-specific header, which might set things that
 are needed by any of the other headers, including system headers. */
@@ -53,7 +55,7 @@ making unique names. */
 #define LOCALHOST_MAX  10
 #endif
 
-/* If not overriden by os.h, dynamic libraries have filenames ending .so */
+/* If not overridden by os.h, dynamic libraries have filenames ending .so */
 #ifndef DYNLIB_FN_EXT
 # define DYNLIB_FN_EXT "so"
 #endif