diff --git a/src/util.jl b/src/util.jl
index df7d7378..1dc2168d 100644
--- a/src/util.jl
+++ b/src/util.jl
@@ -96,6 +96,16 @@ julia> redirect_stdout(devnull) do
 ```
 """
 function trixi_include(mod::Module, example::AbstractString; kwargs...)
+    # Check that all kwargs exist as assignments
+    code = read(example, String)
+    expr = Meta.parse("begin \n$code \nend")
+    expr = insert_maxiters(expr)
+
+    for (key, val) in kwargs
+        # This will throw an error when `key` is not found
+        find_assignment(expr, key)
+    end
+
     Base.include(ex -> replace_assignments(insert_maxiters(ex); kwargs...), mod, example)
 end
 
@@ -282,6 +292,7 @@ end
 function find_assignment(expr, destination)
     # declare result to be able to assign to it in the closure
     local result
+    found = false
 
     # find explicit and keyword assignments
     walkexpr(expr) do x
@@ -289,12 +300,17 @@ function find_assignment(expr, destination)
             if (x.head === Symbol("=") || x.head === :kw) &&
                x.args[1] === Symbol(destination)
                 result = x.args[2]
+                found = true
                 # dump(x)
             end
         end
         return x
     end
 
+    if !found
+        throw(ArgumentError("assignment `$destination` not found in expression"))
+    end
+
     result
 end
 
diff --git a/test/test_util.jl b/test/test_util.jl
index 8a356847..81027d90 100644
--- a/test/test_util.jl
+++ b/test/test_util.jl
@@ -41,8 +41,8 @@ macro test_trixi_include(example, args...)
         if (arg.head == :(=) &&
             !(arg.args[1] in (:l2, :linf, :cons_error, :change_waterheight,
                               :change_velocity, :change_momentum, :change_entropy,
-                              :change_entropy_modified, :atol, :rtol, :atol_ints,
-                              :rtol_ints)))
+                              :change_entropy_modified, :lake_at_rest,
+                              :atol, :rtol, :atol_ints, :rtol_ints)))
             push!(kwargs, Pair(arg.args...))
         end
     end