diff --git a/lib/SILGen/SILGenPattern.cpp b/lib/SILGen/SILGenPattern.cpp
index c51dee36085..6eacb24a8cd 100644
--- a/lib/SILGen/SILGenPattern.cpp
+++ b/lib/SILGen/SILGenPattern.cpp
@@ -2617,8 +2617,6 @@ static void emitDiagnoseOfUnexpectedEnumCase(SILGenFunction &SGF,
   ManagedValue metatype = SGF.B.createValueMetatype(loc, metatypeType, value);
 
   Substitution sub{switchedValueSwiftType, /*Conformances*/None};
-  auto genericArgsMap =
-      diagnoseFailure->getGenericSignature()->getSubstitutionMap(sub);
 
   SGF.emitApplyOfLibraryIntrinsic(loc, diagnoseFailure, sub,
                                   metatype,