diff --git a/lib/fast486/opgroups.c b/lib/fast486/opgroups.c
index 0a297aed414..754a9d8fc90 100644
--- a/lib/fast486/opgroups.c
+++ b/lib/fast486/opgroups.c
@@ -496,8 +496,8 @@ FAST486_OPCODE_HANDLER(Fast486OpcodeGroup8F)
     if (!Fast486ParseModRegRm(State, AddressSize, &ModRegRm))
     {
         /* Exception occurred - restore SP */
-        if (OperandSize) State->GeneralRegs[FAST486_REG_ESP].Long += sizeof(ULONG);
-        else State->GeneralRegs[FAST486_REG_ESP].LowWord += sizeof(USHORT);
+        if (OperandSize) State->GeneralRegs[FAST486_REG_ESP].Long -= sizeof(ULONG);
+        else State->GeneralRegs[FAST486_REG_ESP].LowWord -= sizeof(USHORT);
 
         return FALSE;
     }