diff --git a/src/cfront.c b/src/cfront.c
index 8e5b316a..35307ae3 100644
--- a/src/cfront.c
+++ b/src/cfront.c
@@ -47,6 +47,7 @@ typedef enum {
     T_close_square,  /* ] */
     T_asterisk,      /* '*' */
     T_divide,        /* / */
+    T_mod,           /* % */
     T_bit_or,        /* | */
     T_bit_xor,       /* ^ */
     T_log_and,       /* && */
@@ -338,6 +339,10 @@ token_t get_next_token()
         skip_whitespace();
         return T_lt;
     }
+    if (next_char == '%') {
+        read_char(1);
+        return T_mod;
+    }
     if (next_char == '>') {
         read_char(0);
         if (next_char == '=') {
@@ -876,6 +881,7 @@ int get_operator_prio(opcode_t op)
         return 12;
     case OP_mul:
     case OP_div:
+    case OP_mod:
         return 13;
     default:
         return 0;
@@ -893,6 +899,8 @@ opcode_t get_operator()
         op = OP_mul;
     else if (lex_accept(T_divide))
         op = OP_div;
+    else if (lex_accept(T_mod))
+        op = OP_mod;
     else if (lex_accept(T_lshift))
         op = OP_lshift;
     else if (lex_accept(T_rshift))
@@ -1357,6 +1365,7 @@ int read_numeric_sconstant()
 int eval_expression_imm(opcode_t op, int op1, int op2)
 {
     /* return immediate result */
+    int tmp = op2;
     int res = 0;
     switch (op) {
     case OP_add:
@@ -1371,6 +1380,16 @@ int eval_expression_imm(opcode_t op, int op1, int op2)
     case OP_div:
         res = op1 / op2;
         break;
+    case OP_mod:
+        /* TODO: provide arithmetic & operation instead of '&=' */
+        /* TODO: do optimization for local expression */
+        tmp &= (tmp - 1);
+        if ((op2 != 0) && (tmp == 0)) {
+            res = op1;
+            res &= (op2 - 1);
+        } else
+            res = op1 % op2;
+        break;
     case OP_lshift:
         res = op1 << op2;
         break;
diff --git a/src/codegen.c b/src/codegen.c
index 9fe1b7f1..51d83154 100644
--- a/src/codegen.c
+++ b/src/codegen.c
@@ -121,6 +121,7 @@ int get_code_length(ir_instr_t *ii)
     case OP_func_exit:
         return 16;
     case OP_exit:
+    case OP_mod:
         return 12;
     case OP_load_data_address:
     case OP_jz:
@@ -367,6 +368,14 @@ void code_generate()
             if (dump_ir == 1)
                 printf("    x%d /= x%d", dest_reg, OP_reg);
             break;
+        case OP_mod:
+            emit(__div(__AL, OP_reg + 1, OP_reg, dest_reg));
+            emit(__mul(__AL, OP_reg, OP_reg, OP_reg + 1));
+            emit(__sub_r(__AL, dest_reg, dest_reg, OP_reg));
+            /* TODO: support percent-sign character (%) in format string */
+            if (dump_ir == 1)
+                printf("    x%d = x%d mod x%d", dest_reg, dest_reg, OP_reg);
+            break;
         case OP_negate:
             emit(__rsb_i(__AL, dest_reg, 0, dest_reg));
             if (dump_ir == 1)
diff --git a/src/defs.h b/src/defs.h
index 814937d0..7f4a17df 100644
--- a/src/defs.h
+++ b/src/defs.h
@@ -68,6 +68,7 @@ typedef enum {
     OP_sub,
     OP_mul,
     OP_div, /* signed division */
+    OP_mod, /* modulo */
     OP_lshift,
     OP_rshift,
     OP_log_and,
diff --git a/tests/driver.sh b/tests/driver.sh
index 529a4ccc..a85554bc 100755
--- a/tests/driver.sh
+++ b/tests/driver.sh
@@ -69,8 +69,8 @@ expr 55 "1 + (2 + (3 + (4 + (5 + (6 + (7 + (8 + (9 + 10))))))))"
 # expr 21 "+1+20"
 # expr 10 "-15+(+35-10)"
 
-# expr 2 "5 % 3"
-# expr 6 "111 % 7"
+expr 2 "5 % 3"
+expr 6 "111 % 7"
 
 expr 1 "10 > 5"
 expr 1 "3+3 > 5"