diff --git a/configure b/configure
index 2d86e71efc..4627d2c1eb 100755
--- a/configure
+++ b/configure
@@ -2344,6 +2344,7 @@ if test "$nettle" != "no"; then
         nettle="yes"
 
         cat > $TMPC << EOF
+#include <stddef.h>
 #include <nettle/pbkdf2.h>
 int main(void) {
      pbkdf2_hmac_sha256(8, NULL, 1000, 8, NULL, 8, NULL);