diff --git a/tests/tests-c-compiler/check-assembly.sh b/tests/tests-c-compiler/check-assembly.sh
index 29734fa9..08420ece 100755
--- a/tests/tests-c-compiler/check-assembly.sh
+++ b/tests/tests-c-compiler/check-assembly.sh
@@ -51,10 +51,24 @@ fi
 OFS=$IFS
 IFS="."
 set $args
+data_dir=$(echo "$1" | sed -e s/check-/data-/)
 shift
 IFS=$OFS
 AFLAGS="$*"
 
+if [ -d ${data_dir} ]; then
+    OPT_DATA_DIR="../${data_dir}"
+else
+    OPT_DATA_DIR=""
+fi
+
+if test "${LIBFUZZER_CFLAGS}" && grep LLVMFuzzer ${source_full} > /dev/null;
+then
+    MAKE_FUZZER=yes
+else
+    MAKE_FUZZER=no
+fi
+
 # Assume the test fails. Will be removed when it passes well.
 testdir=test-${args}
 if [ -f "${testdir}-FAILED" ]; then
@@ -65,13 +79,6 @@ touch "${testdir}-FAILED"
 mkdir -p "${testdir}"
 ln -fns "../${source_full}" "${testdir}"
 
-if test "${LIBFUZZER_CFLAGS}" && grep LLVMFuzzer ${source_full} > /dev/null;
-then
-    MAKE_FUZZER=yes
-else
-    MAKE_FUZZER=no
-fi
-
 asn_module=$(echo "${abs_top_srcdir}/tests/tests-asn1c-compiler/${testno}"-*.asn1)
 
 AUTOGENERATED="# This file is autogenerated by $0 ${source_full} ${AFLAGS}"
@@ -116,7 +123,7 @@ cat <<TARGETS >> "${testdir}/Makefile.targets"
 check-fuzzer:
 TARGETS
 else
-    CHECK_FUZZER="UBSAN_OPTIONS=print_stacktrace=1 ./check-fuzzer -timeout=3 -max_total_time=60 -max_len=512 -detect_leaks=1"
+    CHECK_FUZZER="UBSAN_OPTIONS=print_stacktrace=1 ./check-fuzzer -timeout=3 -max_total_time=60 -max_len=512 -detect_leaks=1 ${OPT_DATA_DIR}"
 cat <<TARGETS >> "${testdir}/Makefile.targets"
 check-fuzzer: \$(OBJS)
 	rm -f ${source_obj}
diff --git a/tests/tests-c-compiler/check-src/check-70.-fwide-types.c b/tests/tests-c-compiler/check-src/check-70.-fwide-types.c
index 5e450b66..8152346e 100644
--- a/tests/tests-c-compiler/check-src/check-70.-fwide-types.c
+++ b/tests/tests-c-compiler/check-src/check-70.-fwide-types.c
@@ -277,6 +277,19 @@ process(const char *fname) {
 	return 1;
 }
 
+#ifdef ENABLE_LIBFUZZER
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+    PDU_t *st = 0;
+    asn_dec_rval_t rval;
+    rval = asn_decode(0, ATS_BASIC_XER, &asn_DEF_PDU, (void **)&st, Data, Size);
+    assert(rval.consumed <= Size);
+    ASN_STRUCT_FREE(asn_DEF_PDU, st);
+    return 0;
+}
+
+#else
+
 int
 main() {
 	DIR *dir;
@@ -309,3 +322,4 @@ main() {
 	return 0;
 }
 
+#endif
diff --git a/tests/tests-c-compiler/check-src/check-70.c b/tests/tests-c-compiler/check-src/check-70.c
index 16e3e2e5..8e27799d 100644
--- a/tests/tests-c-compiler/check-src/check-70.c
+++ b/tests/tests-c-compiler/check-src/check-70.c
@@ -256,6 +256,19 @@ process(const char *fname) {
 	return 1;
 }
 
+#ifdef ENABLE_LIBFUZZER
+
+int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
+    PDU_t *st = 0;
+    asn_dec_rval_t rval;
+    rval = asn_decode(0, ATS_BASIC_XER, &asn_DEF_PDU, (void **)&st, Data, Size);
+    assert(rval.consumed <= Size);
+    ASN_STRUCT_FREE(asn_DEF_PDU, st);
+    return 0;
+}
+
+#else
+
 int
 main() {
 	DIR *dir;
@@ -286,3 +299,4 @@ main() {
 	return 0;
 }
 
+#endif