diff --git a/lib/soft386/common.c b/lib/soft386/common.c
index 71115d495bf..0988a1356c0 100644
--- a/lib/soft386/common.c
+++ b/lib/soft386/common.c
@@ -754,4 +754,14 @@ Soft386Exception(PSOFT386_STATE State, INT ExceptionCode)
     }
 }
 
+inline
+BOOLEAN
+Soft386CalculateParity(UCHAR Number)
+{
+    Number ^= Number >> 1;
+    Number ^= Number >> 2;
+    Number ^= Number >> 4;
+    return !(Number & 1);
+}
+
 /* EOF */
diff --git a/lib/soft386/common.h b/lib/soft386/common.h
index df9ba0a12e9..bd8dc39e7d5 100644
--- a/lib/soft386/common.h
+++ b/lib/soft386/common.h
@@ -15,6 +15,9 @@
 #define FASTCALL __fastcall
 #endif
 
+#define SIGN_FLAG_BYTE 0x80
+#define SIGN_FLAG_WORD 0x8000
+#define SIGN_FLAG_LONG 0x80000000
 #define GET_SEGMENT_RPL(s) ((s) & 3)
 #define GET_SEGMENT_INDEX(s) ((s) & 0xFFF8)
 
@@ -119,6 +122,13 @@ Soft386Exception
     INT ExceptionCode
 );
 
+inline
+BOOLEAN
+Soft386CalculateParity
+(
+    UCHAR Number
+);
+
 #endif // _COMMON_H_
 
 /* EOF */
diff --git a/lib/soft386/opcodes.c b/lib/soft386/opcodes.c
index 9e642946ee6..bda4ca5cbd2 100644
--- a/lib/soft386/opcodes.c
+++ b/lib/soft386/opcodes.c
@@ -88,22 +88,22 @@ Soft386OpcodeHandlers[SOFT386_NUM_OPCODE_HANDLERS] =
     NULL, // TODO: OPCODE 0x3D NOT SUPPORTED
     Soft386OpcodePrefix,
     NULL, // TODO: OPCODE 0x3F NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x40 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x41 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x42 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x43 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x44 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x45 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x46 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x47 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x48 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x49 NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4A NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4B NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4C NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4D NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4E NOT SUPPORTED
-    NULL, // TODO: OPCODE 0x4F NOT SUPPORTED
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeIncrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
+    Soft386OpcodeDecrement,
     NULL, // TODO: OPCODE 0x50 NOT SUPPORTED
     NULL, // TODO: OPCODE 0x51 NOT SUPPORTED
     NULL, // TODO: OPCODE 0x52 NOT SUPPORTED
@@ -444,3 +444,93 @@ Soft386OpcodePrefix(PSOFT386_STATE State, UCHAR Opcode)
 
     return TRUE;
 }
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeIncrement(PSOFT386_STATE State, UCHAR Opcode)
+{
+    ULONG Value;
+    BOOLEAN Size = State->SegmentRegs[SOFT386_REG_CS].Size;
+
+    if (State->PrefixFlags == SOFT386_PREFIX_OPSIZE)
+    {
+        /* The OPSIZE prefix toggles the size */
+        Size = !Size;
+    }
+    else if (State->PrefixFlags != 0)
+    {
+        /* Invalid prefix */
+        Soft386Exception(State, SOFT386_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    /* Make sure this is the right instruction */
+    ASSERT((Opcode & 0xF8) == 0x40);
+
+    if (Size)
+    {
+        Value = ++State->GeneralRegs[Opcode & 0x07].Long;
+
+        State->Flags.Of = (Value == SIGN_FLAG_LONG) ? TRUE : FALSE;
+        State->Flags.Sf = (Value & SIGN_FLAG_LONG) ? TRUE : FALSE;
+    }
+    else
+    {
+        Value = ++State->GeneralRegs[Opcode & 0x07].LowWord;
+
+        State->Flags.Of = (Value == SIGN_FLAG_WORD) ? TRUE : FALSE;
+        State->Flags.Sf = (Value & SIGN_FLAG_WORD) ? TRUE : FALSE;
+    }
+
+    State->Flags.Zf = (Value == 0) ? TRUE : FALSE;
+    State->Flags.Af = ((Value & 0x0F) == 0) ? TRUE : FALSE;
+    State->Flags.Pf = Soft386CalculateParity(LOBYTE(Value));
+
+    /* Return success */
+    return TRUE;
+}
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeDecrement(PSOFT386_STATE State, UCHAR Opcode)
+{
+    ULONG Value;
+    BOOLEAN Size = State->SegmentRegs[SOFT386_REG_CS].Size;
+
+    if (State->PrefixFlags == SOFT386_PREFIX_OPSIZE)
+    {
+        /* The OPSIZE prefix toggles the size */
+        Size = !Size;
+    }
+    else if (State->PrefixFlags != 0)
+    {
+        /* Invalid prefix */
+        Soft386Exception(State, SOFT386_EXCEPTION_UD);
+        return FALSE;
+    }
+
+    /* Make sure this is the right instruction */
+    ASSERT((Opcode & 0xF8) == 0x48);
+
+    if (Size)
+    {
+        Value = --State->GeneralRegs[Opcode & 0x07].Long;
+
+        State->Flags.Of = (Value == (SIGN_FLAG_LONG - 1)) ? TRUE : FALSE;
+        State->Flags.Sf = (Value & SIGN_FLAG_LONG) ? TRUE : FALSE;
+    }
+    else
+    {
+        Value = --State->GeneralRegs[Opcode & 0x07].LowWord;
+
+        State->Flags.Of = (Value == (SIGN_FLAG_WORD - 1)) ? TRUE : FALSE;
+        State->Flags.Sf = (Value & SIGN_FLAG_WORD) ? TRUE : FALSE;
+    }
+
+    State->Flags.Zf = (Value == 0) ? TRUE : FALSE;
+    State->Flags.Af = ((Value & 0x0F) == 0x0F) ? TRUE : FALSE;
+    State->Flags.Pf = Soft386CalculateParity(LOBYTE(Value));
+
+    /* Return success */
+    return TRUE;
+}
diff --git a/lib/soft386/opcodes.h b/lib/soft386/opcodes.h
index 25fec0002f4..b6d63b221ff 100644
--- a/lib/soft386/opcodes.h
+++ b/lib/soft386/opcodes.h
@@ -31,4 +31,20 @@ Soft386OpcodePrefix
     UCHAR Opcode
 );
 
+BOOLEAN
+FASTCALL
+Soft386OpcodeIncrement
+(
+    PSOFT386_STATE State,
+    UCHAR Opcode
+);
+
+BOOLEAN
+FASTCALL
+Soft386OpcodeDecrement
+(
+    PSOFT386_STATE State,
+    UCHAR Opcode
+);
+
 #endif // _OPCODES_H_