diff --git a/lib/Expr/ExprPPrinter.cpp b/lib/Expr/ExprPPrinter.cpp
index 5dd953b525..f100ce2ac5 100644
--- a/lib/Expr/ExprPPrinter.cpp
+++ b/lib/Expr/ExprPPrinter.cpp
@@ -389,6 +389,8 @@ class PPrinter : public ExprPPrinter {
       s->constantValues.print(PC.getStream(), Density::Sparse);
     } else if (auto s = dyn_cast<SymbolicSizeConstantAddressSource>(source)) {
       PC << "UNIMPLEMENTED";
+    } else if (auto s = dyn_cast<UninitializedSource>(source)) {
+      PC << "UNIMPLEMENTED";
     } else if (auto s = dyn_cast<MakeSymbolicSource>(source)) {
       PC << s->name << " " << s->version;
     } else if (auto s = dyn_cast<LazyInitializationSource>(source)) {