diff --git a/src/openrct2-ui/scripting/CustomWindow.cpp b/src/openrct2-ui/scripting/CustomWindow.cpp
index 7848ba63df..cd0683ae7a 100644
--- a/src/openrct2-ui/scripting/CustomWindow.cpp
+++ b/src/openrct2-ui/scripting/CustomWindow.cpp
@@ -94,7 +94,7 @@ namespace OpenRCT2::Ui::Windows
         ImageId Image;
         std::string Text;
         TextAlignment TextAlign;
-        colour_t Colour;
+        colour_t Colour{};
         std::string Tooltip;
         std::vector<std::string> Items;
         std::vector<ListViewItem> ListViewItems;
diff --git a/src/openrct2-ui/windows/Cheats.cpp b/src/openrct2-ui/windows/Cheats.cpp
index 10815a3abb..1ca1f4439c 100644
--- a/src/openrct2-ui/windows/Cheats.cpp
+++ b/src/openrct2-ui/windows/Cheats.cpp
@@ -449,7 +449,7 @@ private:
     char _moneySpinnerText[MONEY_STRING_MAXLENGTH];
     money32 _moneySpinnerValue = CHEATS_MONEY_DEFAULT;
     int32_t _selectedStaffSpeed = 1;
-    int32_t _parkRatingSpinnerValue;
+    int32_t _parkRatingSpinnerValue{};
     int32_t _yearSpinnerValue = 1;
     int32_t _monthSpinnerValue = 1;
     int32_t _daySpinnerValue = 1;
diff --git a/src/openrct2-ui/windows/GuestList.cpp b/src/openrct2-ui/windows/GuestList.cpp
index 1436ce958f..5e36426445 100644
--- a/src/openrct2-ui/windows/GuestList.cpp
+++ b/src/openrct2-ui/windows/GuestList.cpp
@@ -128,7 +128,7 @@ private:
     static constexpr size_t MaxGroups = 240;
 
     TabId _selectedTab{};
-    GuestViewType _selectedView;
+    GuestViewType _selectedView{};
     bool _trackingOnly{};
     std::optional<GuestFilterType> _selectedFilter;
     FilterArguments _filterArguments;
@@ -137,7 +137,7 @@ private:
     size_t _numPages{};
     size_t _selectedPage{};
 
-    GuestViewType _lastFindGroupsSelectedView;
+    GuestViewType _lastFindGroupsSelectedView{};
     uint32_t _lastFindGroupsTick{};
     uint32_t _lastFindGroupsWait{};
     std::vector<GuestGroup> _groups;
diff --git a/src/openrct2-ui/windows/TextInput.cpp b/src/openrct2-ui/windows/TextInput.cpp
index b42899e93a..9256978e84 100644
--- a/src/openrct2-ui/windows/TextInput.cpp
+++ b/src/openrct2-ui/windows/TextInput.cpp
@@ -40,7 +40,7 @@ static rct_widget window_text_input_widgets[] = {
 class TextInputWindow final : public Window
 {
 private:
-    widget_identifier _parentWidget;
+    widget_identifier _parentWidget{};
 
     std::string _title;
     rct_string_id _titleStringId = STR_NONE;
@@ -52,7 +52,7 @@ private:
     std::function<void()> _cancelCallback;
 
     int32_t _cursorBlink{};
-    size_t _maxInputLength;
+    size_t _maxInputLength{};
     std::string _buffer;
 
 public:
diff --git a/src/openrct2/object/StationObject.h b/src/openrct2/object/StationObject.h
index 66300dc11e..0912661414 100644
--- a/src/openrct2/object/StationObject.h
+++ b/src/openrct2/object/StationObject.h
@@ -24,9 +24,9 @@ public:
     rct_string_id NameStringId{};
     uint32_t BaseImageId{};
     uint32_t ShelterImageId{};
-    uint32_t Flags;
-    int32_t Height;
-    uint8_t ScrollingMode;
+    uint32_t Flags{};
+    int32_t Height{};
+    uint8_t ScrollingMode{};
 
     explicit StationObject(const rct_object_entry& entry)
         : Object(entry)