diff --git a/.luacheckrc b/.luacheckrc
index 1e5df27..a88280a 100644
--- a/.luacheckrc
+++ b/.luacheckrc
@@ -4,6 +4,7 @@ return {
         "211", -- Unused local variable.
         "212/self", -- Unused argument self.
         "213", -- Unused loop variable.
+        "214", -- used _ prefix variable (we use this often to indicate private variables, not unused)
         "631", -- Line is too long.
     },
     files = {
diff --git a/mathx.lua b/mathx.lua
index 7afbbcc..502db21 100644
--- a/mathx.lua
+++ b/mathx.lua
@@ -126,20 +126,20 @@ end
 --todo: more easings - back, bounce, elastic
 
 --(internal; use a provided random generator object, or not)
-local function _random(_r, ...)
-	if _r then return _r:random(...) end
+local function _random(rng, ...)
+	if rng then return rng:random(...) end
 	if love then return love.math.random(...) end
 	return math.random(...)
 end
 
 --return a random sign
-function mathx.random_sign(_r)
-	return _random(_r) < 0.5 and -1 or 1
+function mathx.random_sign(rng)
+	return _random(rng) < 0.5 and -1 or 1
 end
 
 --return a random value between two numbers (continuous)
-function mathx.random_lerp(min, max, _r)
-	return mathx.lerp(min, max, _random(_r))
+function mathx.random_lerp(min, max, rng)
+	return mathx.lerp(min, max, _random(rng))
 end
 
 --nan checking