diff --git a/lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp b/lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp
index ffdad057774d1..cca78813f8db1 100644
--- a/lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp
+++ b/lib/SIL/Utils/FieldSensitivePrunedLiveness.cpp
@@ -781,7 +781,7 @@ void FieldSensitiveMultiDefPrunedLiveRange::findBoundariesInBlock(
   LLVM_DEBUG(llvm::dbgs() << "Has multiple defs!\n");
 
   // Handle a live-out or live-within block with potentially multiple defs
-  // unsigned prevCount = boundary.getNumLastUsersAndDeadDefs(bitNo);
+  unsigned prevCount = boundary.getNumLastUsersAndDeadDefs(bitNo);
   bool isLive = isLiveOut;
   for (auto &inst : llvm::reverse(*block)) {
     LLVM_DEBUG(llvm::dbgs() << "Visiting: " << inst);
@@ -861,6 +861,7 @@ void FieldSensitiveMultiDefPrunedLiveRange::findBoundariesInBlock(
                << "    Live at beginning of block! No dead args!\n");
   }
 
-  // assert(prevCount < boundary.getNumLastUsersAndDeadDefs(bitNo) &&
-  //        "findBoundariesInBlock must be called on a live block");
+  assert((isLiveOut ||
+          prevCount < boundary.getNumLastUsersAndDeadDefs(bitNo)) &&
+         "findBoundariesInBlock must be called on a live block");
 }
diff --git a/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift b/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift
index 92cb1bc823325..d943ab243ce2c 100644
--- a/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift
+++ b/test/SILOptimizer/moveonly_addresschecker_diagnostics.swift
@@ -2299,7 +2299,7 @@ func copyableStructsInMoveOnlyStructNonConsuming() {
 // Field Sensitive Tests //
 ///////////////////////////
 
-func fieldSensitiveTestReinitField () {
+func fieldSensitiveTestReinitField() {
     var a = NonTrivialStruct()
     a = NonTrivialStruct()
     classConsume(a.k)
@@ -2307,8 +2307,7 @@ func fieldSensitiveTestReinitField () {
     classUseMoveOnlyWithoutEscaping(a.k)
 }
 
-#if false
-func fieldSensitiveTestReinitFieldMultiBlock1 () {
+func fieldSensitiveTestReinitFieldMultiBlock1() {
     var a = NonTrivialStruct()
     a = NonTrivialStruct()
     classConsume(a.k)
@@ -2318,9 +2317,8 @@ func fieldSensitiveTestReinitFieldMultiBlock1 () {
         classUseMoveOnlyWithoutEscaping(a.k)
     }
 }
-#endif
 
-func fieldSensitiveTestReinitFieldMultiBlock2 () {
+func fieldSensitiveTestReinitFieldMultiBlock2() {
     var a = NonTrivialStruct() // expected-error {{'a' used after consume. Lifetime extension of variable requires a copy}}
     a = NonTrivialStruct()
     classConsume(a.k) // expected-note {{consuming use}}
@@ -2332,8 +2330,7 @@ func fieldSensitiveTestReinitFieldMultiBlock2 () {
     classUseMoveOnlyWithoutEscaping(a.k) // expected-note {{non-consuming use}}
 }
 
-#if false
-func fieldSensitiveTestReinitFieldMultiBlock3 () {
+func fieldSensitiveTestReinitFieldMultiBlock3() {
     var a = NonTrivialStruct()
     a = NonTrivialStruct()
     classConsume(a.k)
@@ -2346,10 +2343,10 @@ func fieldSensitiveTestReinitFieldMultiBlock3 () {
 
     classUseMoveOnlyWithoutEscaping(a.k)
 }
-#endif
 
-#if false
-func fieldSensitiveTestReinitFieldMultiBlock4 () {
+// This test sees what happens if we partially reinit along one path and do a
+// full reinit along another path.
+func fieldSensitiveTestReinitFieldMultiBlock4() {
     var a = NonTrivialStruct()
     a = NonTrivialStruct()
     classConsume(a.k)
@@ -2362,4 +2359,43 @@ func fieldSensitiveTestReinitFieldMultiBlock4 () {
 
     classUseMoveOnlyWithoutEscaping(a.k)
 }
-#endif
+
+func fieldSensitiveTestReinitEnumMultiBlock() {
+    var e = NonTrivialEnum.first // expected-error {{'e' used after consume. Lifetime extension of variable requires a copy}}
+    e = NonTrivialEnum.second(Klass())
+    switch e { // expected-note {{consuming use}}
+    case .second:
+        e = NonTrivialEnum.third(NonTrivialStruct())
+    default:
+        break
+    }
+    nonConsumingUseNonTrivialEnum(e) // expected-note {{non-consuming use}}
+}
+
+func fieldSensitiveTestReinitEnumMultiBlock1() {
+    var e = NonTrivialEnum.first
+    e = NonTrivialEnum.second(Klass())
+    switch e {
+    case .second:
+        e = NonTrivialEnum.third(NonTrivialStruct())
+    default:
+        e = NonTrivialEnum.fourth(CopyableKlass())
+    }
+    nonConsumingUseNonTrivialEnum(e)
+}
+
+func fieldSensitiveTestReinitEnumMultiBlock2() {
+    var e = NonTrivialEnum.first
+    e = NonTrivialEnum.second(Klass())
+    if boolValue {
+        switch e {
+        case .second:
+            e = NonTrivialEnum.third(NonTrivialStruct())
+        default:
+            e = NonTrivialEnum.fourth(CopyableKlass())
+        }
+    } else {
+        e = NonTrivialEnum.third(NonTrivialStruct())
+    }
+    nonConsumingUseNonTrivialEnum(e)
+}