diff --git a/configure b/configure
index e4b1aacd6..b39ddb2b8 100755
--- a/configure
+++ b/configure
@@ -514,6 +514,8 @@ process_toolchain() {
         check_add_cflags -Wpointer-arith
         check_add_cflags -Wtype-limits
         check_add_cflags -Wcast-qual
+        check_add_cflags -Wundef
+        check_add_cflags -Wvla
         enabled extra_warnings || check_add_cflags -Wno-unused-function
     fi
 
diff --git a/vp8/encoder/rdopt.c b/vp8/encoder/rdopt.c
index e9e5550a2..ee6b247e4 100644
--- a/vp8/encoder/rdopt.c
+++ b/vp8/encoder/rdopt.c
@@ -3287,7 +3287,7 @@ void vp8_rd_pick_inter_mode(VP8_COMP *cpi, MACROBLOCK *x, int recon_yoffset, int
                       && this_mode != B_PRED
                       && this_mode != I8X8_PRED);
 
-#if CONFIGURE_TX16X16
+#if CONFIG_TX16X16
         if (this_mode <= TM_PRED ||
             this_mode == NEWMV ||
             this_mode == ZEROMV ||
diff --git a/vp8/encoder/tokenize.h b/vp8/encoder/tokenize.h
index 4d2c74eb3..baff4c2b0 100644
--- a/vp8/encoder/tokenize.h
+++ b/vp8/encoder/tokenize.h
@@ -37,6 +37,7 @@ extern int mb_is_skippable(MACROBLOCKD *x, int has_y2_block);
 extern int mby_is_skippable_8x8(MACROBLOCKD *x);
 extern int mbuv_is_skippable_8x8(MACROBLOCKD *x);
 extern int mb_is_skippable_8x8(MACROBLOCKD *x);
+extern int mb_is_skippable_16x16(MACROBLOCKD *x);
 
 #ifdef ENTROPY_STATS
 void init_context_counters();