diff --git a/tests/strings/strings.cpp b/tests/strings/strings.cpp
index 3d8798699f..65ba92da1b 100644
--- a/tests/strings/strings.cpp
+++ b/tests/strings/strings.cpp
@@ -784,7 +784,7 @@ TEST_CASE("StringToULongLong", "[wxString]")
 
 TEST_CASE("StringToDouble", "[wxString]")
 {
-    double d;
+    double d = 0.0;
     static const struct ToDoubleData
     {
         const wxChar *str;