diff --git a/z80.cpp b/z80.cpp
index 625ad70..107e7e7 100644
--- a/z80.cpp
+++ b/z80.cpp
@@ -1601,7 +1601,7 @@ namespace z80
     void IX_INSTRUCTIONS()
     {
         const uint8_t opcode = READ_M1();
-        uint8_t d;
+        int8_t d;
 
         switch (opcode)
         {
@@ -1821,7 +1821,7 @@ namespace z80
 
     void IX_BIT_INSTRUCTIONS()
     {
-        const uint8_t d = READ_MEM_8();
+        const int8_t d = READ_MEM_8();
         const uint8_t opcode = READ_MEM_8();
         t+=3;
         switch (opcode)
@@ -2181,7 +2181,7 @@ namespace z80
     void IY_INSTRUCTIONS()
     {
         const uint8_t opcode = READ_M1();
-        uint8_t d;
+        int8_t d;
 
         switch (opcode)
         {
@@ -2401,7 +2401,7 @@ namespace z80
 
     void IY_BIT_INSTRUCTIONS()
     {
-        const uint8_t d = READ_MEM_8();
+        const int8_t d = READ_MEM_8();
         const uint8_t opcode = READ_MEM_8();
         t+=3;
         switch (opcode)