diff --git a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
--- a/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
+++ b/llvm/lib/ExecutionEngine/ExecutionEngine.cpp
@@ -624,10 +624,12 @@
         }
       }
       break;
-      case Type::FixedVectorTyID:
       case Type::ScalableVectorTyID:
+        report_fatal_error(
+            "Scalable vector support not yet implemented in ExecutionEngine");
+      case Type::FixedVectorTyID:
         // if the whole vector is 'undef' just reserve memory for the value.
-        auto *VTy = cast<VectorType>(C->getType());
+        auto *VTy = cast<FixedVectorType>(C->getType());
         Type *ElemTy = VTy->getElementType();
         unsigned int elemNum = VTy->getNumElements();
         Result.AggregateVal.resize(elemNum);
@@ -927,9 +929,9 @@
         elemNum = CDV->getNumElements();
         ElemTy = CDV->getElementType();
     } else if (CV || CAZ) {
-        auto* VTy = cast<VectorType>(C->getType());
-        elemNum = VTy->getNumElements();
-        ElemTy = VTy->getElementType();
+      auto *VTy = cast<FixedVectorType>(C->getType());
+      elemNum = VTy->getNumElements();
+      ElemTy = VTy->getElementType();
     } else {
         llvm_unreachable("Unknown constant vector type!");
     }
@@ -1100,7 +1102,8 @@
   }
   case Type::FixedVectorTyID:
   case Type::ScalableVectorTyID: {
-    auto *VT = cast<VectorType>(Ty);
+    // FIXME: this needs to handle scalable vectors correctly
+    auto *VT = cast<FixedVectorType>(Ty);
     Type *ElemT = VT->getElementType();
     const unsigned numElems = VT->getNumElements();
     if (ElemT->isFloatTy()) {