diff --git a/tests/strings/vararg.cpp b/tests/strings/vararg.cpp
index 8b555b7220..b2a5140b0a 100644
--- a/tests/strings/vararg.cpp
+++ b/tests/strings/vararg.cpp
@@ -196,7 +196,7 @@ TEST_CASE("ArgsValidation", "[wxString][vararg][error]")
 {
     int written;
     void *ptr = &written;
-    short int swritten;
+    short int swritten = 0;
     wxUnusedVar(swritten); // We're not really going to use it.
 
     // these are valid: