diff --git a/src/generic/imaglist.cpp b/src/generic/imaglist.cpp
index 2a768cd12f..e78522633f 100644
--- a/src/generic/imaglist.cpp
+++ b/src/generic/imaglist.cpp
@@ -125,6 +125,7 @@ int wxGenericImageList::Add( const wxBitmap &bitmap )
     // Cannot add image to invalid list
     wxCHECK_MSG( m_size != wxSize(0, 0), -1, "Invalid image list" );
 
+    const int index = GetImageCount();
     const wxSize bitmapSize = bitmap.GetSize();
 
     // There is a special case: a bitmap may contain more than one image,
@@ -155,7 +156,7 @@ int wxGenericImageList::Add( const wxBitmap &bitmap )
         return -1;
     }
 
-    return GetImageCount() - 1;
+    return index;
 }
 
 int wxGenericImageList::Add( const wxBitmap& bitmap, const wxBitmap& mask )
diff --git a/tests/graphics/imagelist.cpp b/tests/graphics/imagelist.cpp
index 4e564ff91a..7823009dfc 100644
--- a/tests/graphics/imagelist.cpp
+++ b/tests/graphics/imagelist.cpp
@@ -569,6 +569,14 @@ TEST_CASE_METHOD(ImageListTestCase,
         CHECK(HasMaskOrAlpha(bmp2));
         CHECK(bmp2.GetSize() == BITMAP_SIZE);
     }
+
+    SECTION("Add 2x width image")
+    {
+        il.RemoveAll();
+        int idx = il.Add(wxBitmap(BITMAP_SIZE.x * 2, BITMAP_SIZE.y));
+        CHECK(idx == 0);
+        CHECK(il.GetImageCount() == 2);
+    }
 }
 
 TEST_CASE("ImageList:NegativeTests", "[imagelist][negative]")