diff --git a/string_distance.lua b/string_distance.lua
index 3091744..f9a90ea 100644
--- a/string_distance.lua
+++ b/string_distance.lua
@@ -175,9 +175,11 @@ local function strings_with_highest_similarity (str, list_of_other_str)
     -- the output list is the most similar.
 
     -- Error checking
-    assert(type(str) == 'string')
-    assert(type(list_of_other_str) == 'table')
-    for i = 1, #list_of_other_str do  assert(type(list_of_other_str[i]) == 'string')  end
+    if type(str) ~= 'string' then  error(('[errors/internal]: Bad argument #1, expected string, got %s (%s)'):format(str, type(str))) end
+    if type(list_of_other_str) ~= 'table'  then  error(('[errors/internal]: Bad argument #2, expected table, got %s (%s)'):format(list_of_other_str, type(list_of_other_str))) end
+    for i = 1, #list_of_other_str do
+        if type(list_of_other_str[i]) ~= 'string'  then  error(('[errors/internal]: Bad argument #2, expected sequence of strings, but got %s (%s) on index %i'):format(list_of_other_str[i], type(list_of_other_str[i])), i) end
+    end
 
     -- Do work
     local possible = {}