diff --git a/test/Makefile b/test/Makefile
index 3b7c49b..f3c5138 100644
--- a/test/Makefile
+++ b/test/Makefile
@@ -1,8 +1,10 @@
 all:
 	@make -C example_1
 	@make -C stackoverflow
+	@make -C custom_syscall
 
 clean:
 	make -C example_1 clean
 	make -C stackoverflow clean
+	make -C custom_syscall
 
diff --git a/test/custom_syscall/Makefile b/test/custom_syscall/Makefile
new file mode 100644
index 0000000..07ba1b0
--- /dev/null
+++ b/test/custom_syscall/Makefile
@@ -0,0 +1,33 @@
+C_COMPILER=gcc
+
+UNITY_ROOT=../unity
+
+CFLAGS=-std=c99
+CFLAGS += -Wall
+CFLAGS += -Werror
+CFLAGS += -DUVM32_MEMORY_SIZE=16384
+
+SUITE_NAME=tests
+
+TARGET_BASE1=test1
+TARGET1 = $(TARGET_BASE1)
+SRC_FILES1=$(UNITY_ROOT)/src/unity.c test/${SUITE_NAME}.c  test/test_runners/${SUITE_NAME}_Runner.c ../../uvm32/uvm32.c
+INC_DIRS=-I$(UNITY_ROOT)/src -I../../uvm32/ -I../../common -Irom
+
+.PHONY: rom
+
+default: $(SRC_FILES1) rom
+	@$(C_COMPILER) $(CFLAGS) $(INC_DIRS) $(SYMBOLS) $(SRC_FILES1) rom/rom-header.c -o $(TARGET1)
+	@- ./$(TARGET1)
+
+rom:
+	@(cd rom && make)
+
+test/test_runners/${SUITE_NAME}_Runner.c: test/${SUITE_NAME}.c
+	@mkdir -p test/test_runners
+	@ruby $(UNITY_ROOT)/auto/generate_test_runner.rb test/${SUITE_NAME}.c  test/test_runners/${SUITE_NAME}_Runner.c
+
+clean:
+	rm -rf $(TARGET1) test/test_runners
+	(cd rom && make clean)
+
diff --git a/test/custom_syscall/rom/Makefile b/test/custom_syscall/rom/Makefile
new file mode 100644
index 0000000..4698f22
--- /dev/null
+++ b/test/custom_syscall/rom/Makefile
@@ -0,0 +1,13 @@
+TOPDIR=../../../
+PROJECT:=$(shell basename ${PWD})
+SRCS=${PROJECT}.c ${TOPDIR}/apps/crt0.S
+all: all_common
+	@# Convert ROM to C file and header
+	@xxd -i ${PROJECT}.bin > ${PROJECT}-header.c
+	@echo "extern unsigned char ${PROJECT}_bin[]; extern int ${PROJECT}_bin_len;" > ${PROJECT}-header.h
+
+test: test_common
+clean: clean_common
+	rm -f ${PROJECT}-header.h ${PROJECT}-header.c
+
+include ${TOPDIR}/apps/makefile.common
diff --git a/test/custom_syscall/rom/rom.c b/test/custom_syscall/rom/rom.c
new file mode 100644
index 0000000..a5dae81
--- /dev/null
+++ b/test/custom_syscall/rom/rom.c
@@ -0,0 +1,10 @@
+#include "uvm32_target.h"
+
+void main(void) {
+    if (0xAABBCCDD == syscall(0xDEADBEEF, 0xABCD1234, 0xDECAFBAD)) {
+        print("ok");
+    } else {
+        print("fail");
+    }
+}
+
diff --git a/test/custom_syscall/test/tests.c b/test/custom_syscall/test/tests.c
new file mode 100644
index 0000000..901b79c
--- /dev/null
+++ b/test/custom_syscall/test/tests.c
@@ -0,0 +1,62 @@
+#include <string.h>
+#include "unity.h"
+#include "uvm32.h"
+#include "../common/uvm32_common_custom.h"
+
+#include "rom-header.h"
+
+static uvm32_state_t vmst;
+static uvm32_evt_t evt;
+
+void setUp(void) {
+    // runs before each test
+    uvm32_init(&vmst);
+    uvm32_load(&vmst, rom_bin, rom_bin_len);
+}
+
+void tearDown(void) {
+}
+
+void test_custom_syscall_normal(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    // check for custom syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, 0xDEADBEEF);
+    TEST_ASSERT_EQUAL(0xABCD1234, uvm32_getval(&vmst, &evt, ARG0));
+    TEST_ASSERT_EQUAL(0xDECAFBAD, uvm32_getval(&vmst, &evt, ARG1));
+    uvm32_setval(&vmst, &evt, RET, 0xAABBCCDD);
+
+    uvm32_run(&vmst, &evt, 100);
+    // check for print syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINT);
+    const char *str = uvm32_getcstr(&vmst, &evt, ARG0);
+    TEST_ASSERT_EQUAL(0, strcmp(str, "ok"));
+    // run vm to completion
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_END);
+}
+
+void test_custom_syscall_badval(void) {
+    // run the vm
+    uvm32_run(&vmst, &evt, 100);
+    // check for custom syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, 0xDEADBEEF);
+    TEST_ASSERT_EQUAL(0xABCD1234, uvm32_getval(&vmst, &evt, ARG0));
+    TEST_ASSERT_EQUAL(0xDECAFBAD, uvm32_getval(&vmst, &evt, ARG1));
+    uvm32_setval(&vmst, &evt, RET, 0);  // send value that is not being expected
+
+    uvm32_run(&vmst, &evt, 100);
+    // check for print syscall
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_SYSCALL);
+    TEST_ASSERT_EQUAL(evt.data.syscall.code, UVM32_SYSCALL_PRINT);
+    const char *str = uvm32_getcstr(&vmst, &evt, ARG0);
+    TEST_ASSERT_EQUAL(0, strcmp(str, "fail"));
+    // run vm to completion
+    uvm32_run(&vmst, &evt, 100);
+    TEST_ASSERT_EQUAL(evt.typ, UVM32_EVT_END);
+}
+
+