diff --git a/op00.py b/op00.py
index 3b7f7f8..3a2dae4 100644
--- a/op00.py
+++ b/op00.py
@@ -122,7 +122,7 @@ def op00_54_neg(cpu, inst, opsize=2):
 
     cpu.psw_n = newval & cpu.SIGN816[opsize]
     cpu.psw_z = (newval == 0)
-    cpu.psw_v = (val == newval)    # happens at the maximum negative value
+    cpu.psw_v = (val == newval) and (val != 0)  # happens at max neg value
     cpu.psw_c = (newval != 0)
 
     cpu.operandx(xb6, newval, opsize=opsize)