diff --git a/cpu.cpp b/cpu.cpp
index 73f2411..f5e0f2c 100644
--- a/cpu.cpp
+++ b/cpu.cpp
@@ -402,7 +402,7 @@ gam_rc_t cpu::getGAM(const uint8_t mode, const uint8_t reg, const word_mode_t wo
 		case 3:  // @(Rn)+  /  @#a
 			g.addr  = b->read(getRegister(reg, mode_selection), wm_word, mode_selection, false, isR7_space);
 			// might be wrong: the adds should happen when the read is really performed, because of traps
-			addRegister(reg, mode_selection, 2);
+			addRegister(reg, mode_selection, word_mode == wm_byte ? 1 : 2);
 			addToMMR1(mode, reg, word_mode);
 			g.space = d_space;
 			if (read_value)