diff --git a/pyads/constants.py b/pyads/constants.py
index 9ca252f..d89f23e 100644
--- a/pyads/constants.py
+++ b/pyads/constants.py
@@ -127,7 +127,7 @@ class PLCTYPE_WSTRING:
 
 ads_type_to_ctype = {
     # ADST_VOID
-    ADST_INT8: PLCTYPE_BYTE,
+    ADST_INT8: PLCTYPE_SINT,
     ADST_UINT8: PLCTYPE_UBYTE,
     ADST_INT16: PLCTYPE_INT,
     ADST_UINT16: PLCTYPE_UINT,