diff --git a/bin/tools/mdig.c b/bin/tools/mdig.c
index 339b75644a..ddfddee46d 100644
--- a/bin/tools/mdig.c
+++ b/bin/tools/mdig.c
@@ -1594,7 +1594,7 @@ plus_option(char *option, struct query *query, bool global) {
 		FULLCHECK("yaml");
 		yaml = state;
 		if (state) {
-			display_rrcomments = state;
+			display_rrcomments = 1;
 		}
 		break;
 	case 'z': /* zflag */
diff --git a/cocci/implicit_casts_warning.spatch b/cocci/implicit_casts_warning.spatch
new file mode 100644
index 0000000000..1f2e10cc91
--- /dev/null
+++ b/cocci/implicit_casts_warning.spatch
@@ -0,0 +1,56 @@
+@bool_into_int_warning@
+position p;
+int i;
+bool b;
+@@
+i = b@p;
+
+@script:python@
+p << bool_into_int_warning.p;
+@@
+report = coccilib.report.build_report(p[0], "WARNING: implicit bool->int cast on assignment")
+sys.stderr.write(report)
+
+
+
+@return_isc_result_t_into_bool_warning@
+position p;
+isc_result_t result;
+identifier fn;
+identifier literalresult =~ "ISC_R_.*|DNS_R_.*|DST_R_.*|ISCCC_R_.*";
+@@
+bool fn(...) {
+<...
+(
+return result@p;
+|
+return literalresult@p;
+)
+...>
+}
+
+@script:python@
+p << return_isc_result_t_into_bool_warning.p;
+@@
+report = coccilib.report.build_report(p[0], "WARNING: implicit isc_result_t->bool cast on return value")
+sys.stderr.write(report)
+
+
+
+@isc_result_t_into_bool_warning@
+position p;
+isc_result_t result;
+identifier literalresult =~ "ISC_R_.*|DNS_R_.*|DST_R_.*|ISCCC_R_.*";
+bool b;
+@@
+(
+b = result@p;
+|
+b = literalresult@p;
+)
+
+@script:python@
+p << isc_result_t_into_bool_warning.p;
+@@
+report = coccilib.report.build_report(p[0], "WARNING: implicit isc_result_t->bool cast on assignment")
+sys.stderr.write(report)
diff --git a/util/check-cocci.sh b/util/check-cocci.sh
index 09783ea9af..f9f7acbbbb 100755
--- a/util/check-cocci.sh
+++ b/util/check-cocci.sh
@@ -23,7 +23,7 @@ run_spatch() {
   echo "Applying semantic patch $spatch..."
   spatch --jobs "${TEST_PARALLEL_JOBS:-1}" --sp-file "$spatch" --use-gitgrep --dir "." --include-headers $spatchargs >>"$patch" 2>cocci.stderr
   cat cocci.stderr
-  if grep -q -e "parse error" -e "EXN: Failure" cocci.stderr; then
+  if grep -q -e "parse error" -e "EXN: Failure" -e "WARNING" cocci.stderr; then
     ret=1
   fi
   if [ "$(wc <"$patch" -l)" -gt "0" ]; then