diff --git a/ghc/compiler/utils/Argv.lhs b/ghc/compiler/utils/Argv.lhs
index 478dcb1482c3058c196d8a2c3936f6edc1574fad..c9fc6a589b3d8b15aadd134fd38532b353997348 100644
--- a/ghc/compiler/utils/Argv.lhs
+++ b/ghc/compiler/utils/Argv.lhs
@@ -13,6 +13,7 @@ import PreludeGlaST	( indexAddrOffAddr )
 #endif
 
 CHK_Ubiq() -- debugging consistency check
+IMP_FASTSTRING()
 
 #if __GLASGOW_HASKELL__ == 201
 # define ADDR	    GHCbase.Addr