diff --git a/configure.ac b/configure.ac
index 0c1c1e2d789..4615717094b 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1804,6 +1804,7 @@ AS_IF([test $gl_gcc_warnings = no],
   nw="$nw -Wsync-nand"              # irrelevant here, and provokes ObjC warning
   nw="$nw -Wunsafe-loop-optimizations" # OK to suppress unsafe optimizations
   nw="$nw -Wbad-function-cast"      # These casts are no worse than others.
+  nw="$nw -Wzero-as-null-pointer-constant" # Emacs is not yet C2y-safe.
 
   # Emacs doesn't care about shadowing; see
   # <https://lists.gnu.org/r/emacs-diffs/2011-11/msg00265.html>.