dumpprivkey problem (resolved. compressed address <> uncompressed address)

I need the private key for an address in my wallet. I unlocked the wallet, used dumpprivkey and it gave me something of the form

Kzb...

My understanding is that this is the WIF for a "compressed" private key and is base58 for

x80 (prefix byte) [32 bytes (actual private key)] x01 [4 bytes (checksum)]

However, when I extract those 32 bytes as a big-endian 256-bit number and compute the public key and address from it, I do not get the address I started with.

Am I misunderstanding the format of the private key? If not, maybe I'll generate a fresh empty wallet and post full details with an unused address and the result of dumpprivkey.

I'm using bitcoin-qt 0.9.3 on linux (Tails).
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Edit: Never mind. I get the right public key. I was computing an "uncompressed address" from it though. I need to compute a "compressed address."