diff --git a/res/scripts/stdmin.lua b/res/scripts/stdmin.lua
index c3c3d2f0..f2201d94 100644
--- a/res/scripts/stdmin.lua
+++ b/res/scripts/stdmin.lua
@@ -45,7 +45,7 @@ local canvas_ffi_buffer_size = 0
 local _ffi = ffi
 function __vc_Canvas_set_data(self, data)
     if type(data) == "cdata" then
-        self:_set_data(tostring(_ffi.cast("uintptr_t", data)))
+        self:_set_data(tostring(_ffi.cast("uintptr_t", data.bytes)), data.size)
     end
     local width = self.width
     local height = self.height
@@ -60,7 +60,7 @@ function __vc_Canvas_set_data(self, data)
     for i=0, size - 1 do
         canvas_ffi_buffer[i] = data[i + 1]
     end
-    self:_set_data(tostring(_ffi.cast("uintptr_t", canvas_ffi_buffer)))
+    self:_set_data(tostring(_ffi.cast("uintptr_t", canvas_ffi_buffer)), data.size)
 end
 
 local ipairs_mt_supported = false
diff --git a/src/logic/scripting/lua/usertypes/lua_type_canvas.cpp b/src/logic/scripting/lua/usertypes/lua_type_canvas.cpp
index 54bbf654..a7317292 100644
--- a/src/logic/scripting/lua/usertypes/lua_type_canvas.cpp
+++ b/src/logic/scripting/lua/usertypes/lua_type_canvas.cpp
@@ -220,6 +220,14 @@ static int l_set_data(State* L) {
 
     if (lua::isstring(L, 2)) {
         auto ptr = reinterpret_cast<ubyte*>(std::stoull(lua::tostring(L, 2)));
+        int len = lua::touinteger(L, 3);
+        if (len < image.getDataSize()) {
+            throw std::runtime_error(
+                "data size mismatch expected " +
+                std::to_string(image.getDataSize()) + ", got " +
+                std::to_string(len)
+            );
+        }
         std::memcpy(data, ptr, image.getDataSize());
         return 0;
     }