diff --git a/ghc/compiler/nativeGen/MachRegs.lhs b/ghc/compiler/nativeGen/MachRegs.lhs
index 0b01a618de5911a3ce1153fac43cedc14a3571d0..06cbae164e99a85a9ef23fbf70dfd8e000ccc374 100644
--- a/ghc/compiler/nativeGen/MachRegs.lhs
+++ b/ghc/compiler/nativeGen/MachRegs.lhs
@@ -94,7 +94,7 @@ dblImmLit r
 	 IF_ARCH_alpha({-prepend nothing-}
 	,IF_ARCH_i386( '0' : 'd' :
 	,IF_ARCH_sparc('0' : 'r' :,)))
-	show (rational r))
+	showSDoc (rational r))
 \end{code}
 
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