ghc panic in kindFunResult

The compiler made me post this bug report. Unfortunately I don't have a minimal example to reproduce it...

ghc: panic! (the 'impossible' happened)
  (GHC version 7.4.1 for i386-apple-darwin):
	kindFunResult
    ( k_a2Yio{tv} [tau] :: ghc-prim:GHC.Prim.BOX{(w) tc 347} )

Trac metadata

Trac field	Value
Version	7.4.1
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Compiler
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