diff --git a/src/execute.c b/src/execute.c
index 837dd0c..ef5763b 100644
--- a/src/execute.c
+++ b/src/execute.c
@@ -74,7 +74,9 @@ static dword readRegister(Machine *state, a64inst_regSpecifier reg, a64inst_regT
 // and truncating the value being written when it can't fit in the specified register
 static void writeRegister(Machine *state, a64inst_regSpecifier reg, a64inst_regType regType, dword value) {
     assert(reg <= REGISTER_COUNT);
-    state->registers[reg] = truncateValue(value, regType);
+    if (reg != ZERO_REGISTER) {
+        state->registers[reg] = truncateValue(value, regType);
+    }
 }
 
 // Returns the position of the MSB of the given register type