diff --git a/src/cron/expression/c/expression.h b/src/cron/expression/c/expression.h
new file mode 100644
index 0000000..079a72a
--- /dev/null
+++ b/src/cron/expression/c/expression.h
@@ -0,0 +1,20 @@
+#include <time.h>
+#include <stdint.h>
+
+typedef struct cron_expression {
+    uint8_t *minutes;
+    uint8_t *hours;
+    uint8_t *days;
+    uint8_t *months;
+    uint8_t minute_count;
+    uint8_t hour_count;
+    uint8_t day_count;
+    uint8_t month_count;
+} CronExpression;
+
+/**
+ * Given a 
+ */
+int ce_next(struct tm *out, struct tm *ref);
+
+int ce_parse(CronExpression *out, char *s);