diff --git a/lib/Sema/CSDiagnostics.cpp b/lib/Sema/CSDiagnostics.cpp
index 3949ae2b4981b..7dfa649ff42ec 100644
--- a/lib/Sema/CSDiagnostics.cpp
+++ b/lib/Sema/CSDiagnostics.cpp
@@ -680,7 +680,7 @@ bool MissingConformanceFailure::diagnoseAsAmbiguousOperatorRef() {
   // about missing conformance just in case.
   auto operatorID = name.getIdentifier();
 
-  auto *applyExpr = cast_or_null<ApplyExpr>(findParentExpr(anchor));
+  auto *applyExpr = cast<ApplyExpr>(findParentExpr(anchor));
   if (auto *binaryOp = dyn_cast<BinaryExpr>(applyExpr)) {
     auto lhsType = getType(binaryOp->getArg()->getElement(0));
     auto rhsType = getType(binaryOp->getArg()->getElement(1));
diff --git a/lib/Sema/ConstraintSystem.cpp b/lib/Sema/ConstraintSystem.cpp
index 53395f6e4e7e6..b8c658435bef4 100644
--- a/lib/Sema/ConstraintSystem.cpp
+++ b/lib/Sema/ConstraintSystem.cpp
@@ -2425,7 +2425,7 @@ bool ConstraintSystem::salvage(SmallVectorImpl<Solution> &viable, Expr *expr) {
 
     // Before removing any "fixed" solutions, let's check
     // if ambiguity is caused by fixes and diagnose if possible.
-    if (diagnoseAmbiguityWithFixes(expr, viable))
+    if (diagnoseAmbiguityWithFixes(viable))
       return true;
 
     // FIXME: If we were able to actually fix things along the way,
@@ -2529,7 +2529,7 @@ static void diagnoseOperatorAmbiguity(ConstraintSystem &cs,
 }
 
 bool ConstraintSystem::diagnoseAmbiguityWithFixes(
-    Expr *expr, ArrayRef<Solution> solutions) {
+    ArrayRef<Solution> solutions) {
   if (solutions.empty())
     return false;
 
diff --git a/lib/Sema/ConstraintSystem.h b/lib/Sema/ConstraintSystem.h
index c5aa1c80a2873..5ba8e83f2c095 100644
--- a/lib/Sema/ConstraintSystem.h
+++ b/lib/Sema/ConstraintSystem.h
@@ -2108,7 +2108,7 @@ class ConstraintSystem {
   void diagnoseFailureForExpr(Expr *expr);
 
   bool diagnoseAmbiguity(Expr *expr, ArrayRef<Solution> solutions);
-  bool diagnoseAmbiguityWithFixes(Expr *expr, ArrayRef<Solution> solutions);
+  bool diagnoseAmbiguityWithFixes(ArrayRef<Solution> solutions);
 
   /// Give the deprecation warning for referring to a global function
   /// when there's a method from a conditional conformance in a smaller/closer