diff --git a/lib/Backend/GlobOpt.cpp b/lib/Backend/GlobOpt.cpp
index 6a1cc9de1a9..3087b08d586 100644
--- a/lib/Backend/GlobOpt.cpp
+++ b/lib/Backend/GlobOpt.cpp
@@ -13375,6 +13375,7 @@ GlobOpt::CheckJsArrayKills(IR::Instr *const instr)
                     case IR::HelperArray_Shift:
                     case IR::HelperArray_Splice:
                     case IR::HelperArray_Unshift:
+                    case IR::HelperArray_Concat:
                         kills.SetKillsArrayHeadSegments();
                         kills.SetKillsArrayHeadSegmentLengths();
                         break;
@@ -13404,6 +13405,7 @@ GlobOpt::CheckJsArrayKills(IR::Instr *const instr)
                     //case IR::HelperArray_Sort:
                     case IR::HelperArray_Splice:
                     case IR::HelperArray_Unshift:
+                    case IR::HelperArray_Concat:
                         kills.SetKillsNativeArrays();
                         break;
                 }
diff --git a/lib/Backend/GlobOptExpr.cpp b/lib/Backend/GlobOptExpr.cpp
index 2af0dbd129a..cc1d4ff0820 100644
--- a/lib/Backend/GlobOptExpr.cpp
+++ b/lib/Backend/GlobOptExpr.cpp
@@ -844,6 +844,7 @@ GlobOpt::ProcessArrayValueKills(IR::Instr *instr)
             case IR::HelperArray_Shift:
             case IR::HelperArray_Unshift:
             case IR::HelperArray_Splice:
+            case IR::HelperArray_Concat:
                 this->currentBlock->globOptData.liveArrayValues->ClearAll();
                 break;
         }