diff --git a/src/d6502/cmos.d b/src/d6502/cmos.d
index b6cd16a..0972594 100644
--- a/src/d6502/cmos.d
+++ b/src/d6502/cmos.d
@@ -225,7 +225,7 @@ class Cmos(bool strict, bool cumulative) : Cpu!(strict, cumulative)
     void opcode5C()
     {
         readByteOperand();
-        peek(programCounter);
+        peek(programCounter++);
         peek(0xFF00 | operand1);
         peek(0xFFFF);
         peek(0xFFFF);
diff --git a/src/d6502/nmosundoc.d b/src/d6502/nmosundoc.d
index 3cff407..9c78d3a 100644
--- a/src/d6502/nmosundoc.d
+++ b/src/d6502/nmosundoc.d
@@ -263,7 +263,7 @@ class NmosUndoc(bool strict, bool cumulative) : NmosBase!(strict, cumulative)
     override void opcode8B()
     {
         // unstable
-        readVal = operand1 = readFinal(programCounter);
+        readVal = operand1 = readFinal(programCounter++);
 
         version(Atari8Bit)
         {
@@ -350,7 +350,7 @@ class NmosUndoc(bool strict, bool cumulative) : NmosBase!(strict, cumulative)
     /* SBX #$$ */
     override void opcodeCB()
     {
-        readVal = operand1 = readFinal(programCounter);
+        readVal = operand1 = readFinal(programCounter++);
         xIndex &= accumulator;
         flag.zero_ = flag.negative_ = compare(xIndex, readVal);
     }
@@ -358,7 +358,7 @@ class NmosUndoc(bool strict, bool cumulative) : NmosBase!(strict, cumulative)
     /* SBC #$$ */
     override void opcodeEB()
     {
-        readVal = operand1 = readFinal(programCounter);
+        readVal = operand1 = readFinal(programCounter++);
         if (flag.decimal) dec_subWithCarry(readVal);
         else hex_subWithCarry(readVal);
     }