diff --git a/acinclude.m4 b/acinclude.m4
index 251592dc15d9ae62db55969dc7856745af6aba9a..a53ca78277e19e10ef9da810d1e0174a00bbbab5 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -510,8 +510,10 @@ AC_DEFUN([CURL_CC_DEBUG_OPTS],
          dnl * 279 warns on static conditions in while expressions
          dnl * 269 warns on our "%Od" printf formatters for curl_off_t output:
          dnl   "invalid format string conversion"
+         dnl * 1419 warns on "external declaration in primary source file"
+         dnl   which we know and do on purpose.
 
-         WARN="-wd279,269"
+         WARN="-wd279,269,1419"
 
          if test "$gccnum" -gt "600"; then
             dnl icc 6.0 and older doesn't have the -Wall flag