diff --git a/sha0/main.c b/sha0/main.c
index 6aa82ff..d4bc99f 100644
--- a/sha0/main.c
+++ b/sha0/main.c
@@ -1,8 +1,9 @@
 #include <stdio.h>
 #include <string.h>
+#include "types.h"
 
 // Declare the function from sha0.c
-void Internal_Sha0(unsigned char *dest, const unsigned char *src, const unsigned int size);
+const UCHAR* MY_SHA0_hash(const void* data, int len, UCHAR* digest);
 
 #define SHA0_DIGEST_SIZE 20
 
@@ -12,8 +13,8 @@ int main(int argc, char **argv) {
         return 1;
     }
 
-    unsigned char digest[SHA0_DIGEST_SIZE];
-    Internal_Sha0(digest, (const unsigned char *)argv[1], strlen(argv[1]));
+    UCHAR digest[SHA0_DIGEST_SIZE];
+    MY_SHA0_hash((const UCHAR *)argv[1], strlen(argv[1]), digest);
 
     for (int i = 0; i < SHA0_DIGEST_SIZE; i++) {
         printf("%02x", digest[i]);
diff --git a/sha0/sha0.c b/sha0/sha0.c
index b1e46b0..37a0ff7 100644
--- a/sha0/sha0.c
+++ b/sha0/sha0.c
@@ -1,4 +1,10 @@
-// Copied from softether's Encrypt.c
+// Copied from softether's src/Cedar/Encrypt.c
+
+// define custom types as defined in SoftEther's code
+#include "types.h"
+
+// rest is copied as is
+
 /////////////////////////
 // SHA0 implementation //
 /////////////////////////
@@ -34,13 +40,8 @@
  * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#include <stdlib.h>
 #include <string.h>
 
-typedef unsigned long long UINT64;
-typedef unsigned char UCHAR;
-typedef unsigned int UINT;
-
 #define rol(bits, value) (((value) << (bits)) | ((value) >> (32 - (bits))))
 
 typedef struct MY_SHA0_CTX {
@@ -144,9 +145,4 @@ const UCHAR* MY_SHA0_hash(const void* data, int len, UCHAR* digest) {
 	MY_SHA0_update(&ctx, data, len);
 	memcpy(digest, MY_SHA0_final(&ctx), MY_SHA0_DIGEST_SIZE);
 	return digest;
-}
-
-void Internal_Sha0(unsigned char *dest, const unsigned char *src, const UINT size)
-{
-	MY_SHA0_hash(src, (int)size, dest);
-}
+}
\ No newline at end of file
diff --git a/sha0/types.h b/sha0/types.h
new file mode 100644
index 0000000..4c0523b
--- /dev/null
+++ b/sha0/types.h
@@ -0,0 +1,8 @@
+#ifndef TYPES_H
+#define TYPES_H
+
+typedef unsigned long long UINT64;
+typedef unsigned char UCHAR;
+typedef unsigned int UINT;
+
+#endif