diff --git a/src/filter.c b/src/filter.c
index 70cc2fda..3e4baa5a 100644
--- a/src/filter.c
+++ b/src/filter.c
@@ -1149,8 +1149,8 @@ static void filter_deblock_unit(encoder_state_t * const state,
   // Chroma pixel coordinates.
   const int32_t x_c = x >> 1;
   const int32_t y_c = y >> 1;
-  if ((state->encoder_control->chroma_format != KVZ_CSP_400 && is_on_8x8_grid(x_c, y_c, dir) && (x_c + 4) % 32) 
-      || (x == state->tile->frame->width - 8 && dir == 1 && y_c % 8 == 0)) {
+  if (state->encoder_control->chroma_format != KVZ_CSP_400 && (is_on_8x8_grid(x_c, y_c, dir && (x_c + 4) % 32) 
+                                                               || (x == state->tile->frame->width - 8 && dir == 1 && y_c % 8 == 0))) {
     filter_deblock_edge_chroma(state, x_c, y_c, length, dir, tu_boundary);
   }
 }
diff --git a/src/search.c b/src/search.c
index 9179c9b8..cedebdff 100644
--- a/src/search.c
+++ b/src/search.c
@@ -639,7 +639,7 @@ static double search_cu(encoder_state_t * const state, int x, int y, int depth,
                          NULL, lcu);
 
       // TODO: This heavily relies to square CUs
-      if (depth != 4 || (x % 8 && y % 8) && state->encoder_control->chroma_format != KVZ_CSP_400) {
+      if ((depth != 4 || (x % 8 && y % 8)) && state->encoder_control->chroma_format != KVZ_CSP_400) {
         // There is almost no benefit to doing the chroma mode search for
         // rd2. Possibly because the luma mode search already takes chroma
         // into account, so there is less of a chanse of luma mode being
diff --git a/tests/Makefile.am b/tests/Makefile.am
index 386573d7..cf2ce1db 100644
--- a/tests/Makefile.am
+++ b/tests/Makefile.am
@@ -2,7 +2,8 @@
 TESTS = $(check_PROGRAMS) \
     test_external_symbols.sh \
     test_intra.sh \
-    test_invalid_input.sh
+    test_invalid_input.sh \
+    test_monochrome.sh
     #test_tools.sh
     #test_weird_shapes.sh
 
@@ -10,6 +11,7 @@ EXTRA_DIST = \
     test_external_symbols.sh \
     test_intra.sh \
     test_invalid_input.sh \
+    test_monochrome.sh \
     #test_tools.sh \
     #test_weird_shapes.sh \
     util.sh
diff --git a/tests/test_intra.sh b/tests/test_intra.sh
index aaad7525..039b0497 100755
--- a/tests/test_intra.sh
+++ b/tests/test_intra.sh
@@ -6,7 +6,7 @@ set -eu
 
 . "${0%/*}/util.sh"
 
-common_args='256x128 10 -p1 --preset=ultrafast --threads=0 --no-wpp --no-tmvp --no-deblock --sao=0 --alf=full --cpuid=0 --pu-depth-intra 0-4'
+common_args='256x128 10 yuv420p -p1 --preset=ultrafast --threads=0 --no-wpp --no-tmvp --no-deblock --sao=0 --alf=full --cpuid=0 --pu-depth-intra 0-4'
 valgrind_test $common_args --rd=1
 valgrind_test $common_args --rd=2 --no-transform-skip --qp 37
 valgrind_test $common_args --rd=2 --no-transform-skip --qp 37 --rdoq
diff --git a/tests/test_invalid_input.sh b/tests/test_invalid_input.sh
index b7cf7369..c33f0dae 100755
--- a/tests/test_invalid_input.sh
+++ b/tests/test_invalid_input.sh
@@ -5,4 +5,4 @@
 set -eu
 . "${0%/*}/util.sh"
 
-encode_test 1x65 1 1
+encode_test 1x65 1 yuv420p 1
diff --git a/tests/test_monochrome.sh b/tests/test_monochrome.sh
new file mode 100755
index 00000000..928228d4
--- /dev/null
+++ b/tests/test_monochrome.sh
@@ -0,0 +1,12 @@
+#!/bin/sh
+
+# Test all-intra coding.
+
+set -eu
+
+. "${0%/*}/util.sh"
+
+common_args='256x128 10 gray --hash none --preset=ultrafast --input-format P400 --threads=0 --no-wpp --no-tmvp --no-deblock --sao=0 --cpuid=0 --pu-depth-intra 0-4'
+valgrind_test $common_args --rd=1 -p1 
+valgrind_test $common_args --rd=2 -p1 
+valgrind_test $common_args --rd=2 -p1 --deblock 0:0
diff --git a/tests/test_tools.sh b/tests/test_tools.sh
index ff2a14f3..ca80123a 100755
--- a/tests/test_tools.sh
+++ b/tests/test_tools.sh
@@ -5,7 +5,7 @@
 set -eu
 . "${0%/*}/util.sh"
 
-common_args='264x130 10 -p0 -r1 --threads=2 --wpp --owf=1 --rd=0'
+common_args='264x130 10 yuv420p -p0 -r1 --threads=2 --wpp --owf=1 --rd=0'
 
 valgrind_test $common_args --no-rdoq --no-deblock --no-sao --no-signhide --subme=1 --pu-depth-intra=2-3
 valgrind_test $common_args --no-rdoq --no-signhide --subme=0
diff --git a/tests/test_weird_shapes.sh b/tests/test_weird_shapes.sh
index d6782008..025b7794 100755
--- a/tests/test_weird_shapes.sh
+++ b/tests/test_weird_shapes.sh
@@ -3,6 +3,6 @@
 set -eu
 . "${0%/*}/util.sh"
 
-valgrind_test  16x16  10 --threads=0 --no-wpp --preset=veryslow
-valgrind_test 256x16  10 --threads=0 --no-wpp --preset=veryslow
-valgrind_test  16x256 10 --threads=0 --no-wpp --preset=veryslow
+valgrind_test  16x16  10 yuv420p --threads=0 --no-wpp --preset=veryslow
+valgrind_test 256x16  10 yuv420p --threads=0 --no-wpp --preset=veryslow
+valgrind_test  16x256 10 yuv420p --threads=0 --no-wpp --preset=veryslow
diff --git a/tests/util.sh b/tests/util.sh
index f6d956d6..9658837a 100644
--- a/tests/util.sh
+++ b/tests/util.sh
@@ -22,7 +22,7 @@ prepare() {
     cleanup
     print_and_run \
         ffmpeg -f lavfi -i "mandelbrot=size=${1}" \
-            -vframes "${2}" -pix_fmt yuv420p -f yuv4mpegpipe \
+            -vframes "${2}" -pix_fmt "${3}" -f yuv4mpegpipe \
             "${yuvfile}"
 }
 
@@ -31,8 +31,10 @@ valgrind_test() {
     shift
     frames="$1"
     shift
+    format="$1"
+    shift
 
-    prepare "${dimensions}" "${frames}"
+    prepare "${dimensions}" "${frames}" "${format}"
 
     # If $KVZ_TEST_VALGRIND is defined and equal to "1", run the test with
     # valgrind. Otherwise, run without valgrind.
@@ -59,10 +61,12 @@ encode_test() {
     shift
     frames="$1"
     shift
+    format="$1"
+    shift
     expected_status="$1"
     shift
 
-    prepare "${dimensions}" "${frames}"
+    prepare "${dimensions}" "${frames}" "${format}"
 
     set +e
     print_and_run \