diff --git a/contributors.txt b/contributors.txt
index 230e494f2..f48052823 100644
--- a/contributors.txt
+++ b/contributors.txt
@@ -209,4 +209,5 @@ YYYY/MM/DD, github id, Full name, email
 2018/11/12, vinoski, Steve Vinoski, vinoski@ieee.org
 2018/11/14, nxtstep, Adriaan (Arjan) Duz, codewithadriaan[et]gmail[dot]com
 2018/11/15, amykyta3, Alex Mykyta, amykyta3@users.noreply.github.com
-2018/11/29, hannemann-tamas, Ralf Hannemann-Tamas, ralf.ht@gmail.com
\ No newline at end of file
+2018/11/29, hannemann-tamas, Ralf Hannemann-Tamas, ralf.ht@gmail.com
+2018/12/20, WalterCouto, Walter Couto, WalterCouto@users.noreply.github.com
\ No newline at end of file
diff --git a/runtime/Cpp/runtime/src/atn/PredictionContext.cpp b/runtime/Cpp/runtime/src/atn/PredictionContext.cpp
index 95c54a0d0..597e083a6 100755
--- a/runtime/Cpp/runtime/src/atn/PredictionContext.cpp
+++ b/runtime/Cpp/runtime/src/atn/PredictionContext.cpp
@@ -278,7 +278,7 @@ Ref<PredictionContext> PredictionContext::mergeArrays(const Ref<ArrayPredictionC
       // same payload (stack tops are equal), must yield merged singleton
       size_t payload = a->returnStates[i];
       // $+$ = $
-      bool both$ = payload == EMPTY_RETURN_STATE && a_parent && b_parent;
+      bool both$ = payload == EMPTY_RETURN_STATE && !a_parent && !b_parent;
       bool ax_ax = (a_parent && b_parent) && *a_parent == *b_parent; // ax+ax -> ax
       if (both$ || ax_ax) {
         mergedParents[k] = a_parent; // choose left