diff --git a/llvm/lib/FuzzMutate/IRMutator.cpp b/llvm/lib/FuzzMutate/IRMutator.cpp
index 59f94716caa0a5dda67100141002b8bfa078434e..15e7f86d1cdfc45000987e83c9f8a43663ac14f5 100644
--- a/llvm/lib/FuzzMutate/IRMutator.cpp
+++ b/llvm/lib/FuzzMutate/IRMutator.cpp
@@ -105,6 +105,8 @@ void InjectorIRStrategy::mutate(BasicBlock &BB, RandomIRBuilder &IB) {
   SmallVector<Instruction *, 32> Insts;
   for (auto I = BB.getFirstInsertionPt(), E = BB.end(); I != E; ++I)
     Insts.push_back(&*I);
+  if (Insts.size() < 1)
+    return;
 
   // Choose an insertion point for our new instruction.
   size_t IP = uniform<size_t>(IB.Rand, 0, Insts.size() - 1);