diff --git a/src/DU.h b/src/DU.h
new file mode 100644
index 0000000..e69de29
diff --git a/src/globals.c b/src/globals.c
index 553fb00..dca27e2 100644
--- a/src/globals.c
+++ b/src/globals.c
@@ -524,6 +524,8 @@ void bb_disconnect(basic_block_t *pred, basic_block_t *succ)
 /* The symbol is an argument of function or the variable in declaration */
 void add_symbol(basic_block_t *bb, var_t *var)
 {
+    if (!bb)
+        return;
     symbol_t *sym;
     for (sym = bb->symbol_list.head; sym; sym = sym->next) {
         if (sym->var == var)
diff --git a/tests/driver.sh b/tests/driver.sh
index ec655c9..4859a29 100755
--- a/tests/driver.sh
+++ b/tests/driver.sh
@@ -271,6 +271,15 @@ int main() {
 }
 EOF
 
+# Unreachable declaration should not cause prog seg-falut (prog should leave normally with exit code 0)
+try_ 0 << EOF
+int main()
+{
+    return 0;
+    int a = 5;
+}
+EOF
+
 try_ 1 << EOF
 int is_odd(int x);