diff --git a/A2Mac/common.h b/A2Mac/common.h
index 436de28..74ab6d4 100644
--- a/A2Mac/common.h
+++ b/A2Mac/common.h
@@ -56,7 +56,7 @@ static inline void set_flags_Z( const uint8_t test ) {
     dbgPrintf("%c", m6502.flags.Z ? 'Z' : 'z');
 }
 
-static inline void set_flags_C( const int test ) {
+static inline void set_flags_C( const int16_t test ) {
     m6502.flags.C = test >= 0;
     dbgPrintf("%c", m6502.flags.C ? 'C' : 'c');
 }
@@ -76,7 +76,7 @@ static inline void set_flags_NVZ( const uint8_t test ) {
     set_flags_V(test);
 }
 
-static inline void set_flags_NZC( const int test ) {
+static inline void set_flags_NZC( const int16_t test ) {
     set_flags_NZ(test);
     set_flags_C(test);
 }
diff --git a/A2Mac/instructions/6502_instr_arithmetic.h b/A2Mac/instructions/6502_instr_arithmetic.h
index 425edcf..5599581 100644
--- a/A2Mac/instructions/6502_instr_arithmetic.h
+++ b/A2Mac/instructions/6502_instr_arithmetic.h
@@ -31,7 +31,11 @@
 **/
 static inline void ADC( uint8_t imm ) {
     dbgPrintf("ADC(%02X) A:%02X + %02X ", imm, m6502.A, imm);
-    set_flags_NZCV( m6502.A += imm + m6502.flags.C );
+    
+    int16_t tmp;
+    set_flags_NVZ( m6502.A = tmp = (int16_t)m6502.A + imm + m6502.flags.C );
+    m6502.flags.C = tmp > 0xFF;
+    
     dbgPrintf("-> A:%02X ", m6502.A);
 }
 
diff --git a/A2Mac/instructions/6502_instr_compare_test.h b/A2Mac/instructions/6502_instr_compare_test.h
index ff6fb05..05d8cd2 100644
--- a/A2Mac/instructions/6502_instr_compare_test.h
+++ b/A2Mac/instructions/6502_instr_compare_test.h
@@ -49,7 +49,7 @@ static inline void BIT( uint8_t imm ) {
  **/
 static inline void CMP( uint8_t imm ) {
     dbgPrintf("CMP(%02X) ", imm);
-    set_flags_NZC( (int)m6502.A - imm );
+    set_flags_NZC( (int16_t)m6502.A - imm );
 }
 
 /**
@@ -66,7 +66,7 @@ static inline void CMP( uint8_t imm ) {
  **/
 static inline void CPX( uint8_t imm ) {
     dbgPrintf("CPX(%02X) ", imm);
-    set_flags_NZC( (int)m6502.X - imm );
+    set_flags_NZC( (int16_t)m6502.X - imm );
 }
 
 /**
@@ -83,7 +83,7 @@ static inline void CPX( uint8_t imm ) {
  **/
 static inline void CPY( uint8_t imm ) {
     dbgPrintf("CPY(%02X) ", imm);
-    set_flags_NZC( (int)m6502.Y - imm );
+    set_flags_NZC( (int16_t)m6502.Y - imm );
 }
 
 #endif // __6502_INSTR_COMPARE_TEST_H__
diff --git a/A2Mac/instructions/6502_instr_inc_dec.h b/A2Mac/instructions/6502_instr_inc_dec.h
index ca98382..f018a86 100644
--- a/A2Mac/instructions/6502_instr_inc_dec.h
+++ b/A2Mac/instructions/6502_instr_inc_dec.h
@@ -33,7 +33,7 @@ static inline void INC( uint8_t * dst ) {
  INX  Increment Index X by One
  
  X + 1 -> X                       N Z C I D V
- + + - - - -
+                                  + + - - - -
  
  addressing    assembler    opc  bytes  cyles
  --------------------------------------------
@@ -49,7 +49,7 @@ static inline void INX() {
  INY  Increment Index Y by One
  
  Y + 1 -> Y                       N Z C I D V
- + + - - - -
+                                  + + - - - -
  
  addressing    assembler    opc  bytes  cyles
  --------------------------------------------
diff --git a/A2Mac/instructions/6502_instr_misc.h b/A2Mac/instructions/6502_instr_misc.h
index dec91f0..0a697a4 100644
--- a/A2Mac/instructions/6502_instr_misc.h
+++ b/A2Mac/instructions/6502_instr_misc.h
@@ -28,7 +28,7 @@ static inline void BRK() {
  NOP  No Operation
  
  ---                              N Z C I D V
- - - - - - -
+                                 - - - - - -
  
  addressing    assembler    opc  bytes  cyles
  --------------------------------------------