diff --git a/include/stdlib.h b/include/stdlib.h
index 877b74d..a5fe2ad 100644
--- a/include/stdlib.h
+++ b/include/stdlib.h
@@ -16,5 +16,7 @@ void *calloc(size_t num, size_t sz);
 void *malloc(size_t sz);
 void free(void *buf);
 
+int atoi(const char *nptr);
+
 #endif /* __STDLIB_H__ */
 
diff --git a/lib/libc/SConscript b/lib/libc/SConscript
index d8e511c..f8aa670 100644
--- a/lib/libc/SConscript
+++ b/lib/libc/SConscript
@@ -18,6 +18,7 @@ src_common = [
     "process.c",
     "posix/mman.c",
     "posix/pthread.c",
+    "stdlib.c",
     "string.c",
     "syscall.c",
     "time.c",
diff --git a/lib/libc/stdlib.c b/lib/libc/stdlib.c
new file mode 100644
index 0000000..19c4d12
--- /dev/null
+++ b/lib/libc/stdlib.c
@@ -0,0 +1,18 @@
+
+int
+atoi(const char *nptr)
+{
+    int i = 0;
+    int val = 0;
+
+    while (nptr[i] != '\0') {
+	if (nptr[i] >= '0' && nptr[i] <= '9') {
+	    val = val * 10 + (int)(nptr[i] - '0');
+	} else {
+	    return 0;
+	}
+    }
+
+    return val;
+}
+