diff --git a/lua/src/lib/primes.lua b/lua/src/lib/primes.lua
index 3a2188cf..5b479a3e 100644
--- a/lua/src/lib/primes.lua
+++ b/lua/src/lib/primes.lua
@@ -26,11 +26,17 @@ local function primes(stop)
     local function next()
         if stop and prime >= stop then
             sieve = {}
-            error("Tried to exceed given limit")
+            return nil, "Tried to exceed given limit"
         end
 
         prime = next_prime(candidate)
         candidate = prime + 1
+
+        if stop and prime >= stop then
+            sieve = {}
+            return nil, "Tried to exceed given limit"
+        end
+
         return prime
     end
 
diff --git a/lua/src/p0003.lua b/lua/src/p0003.lua
index e7ea1c4d..3554a240 100644
--- a/lua/src/p0003.lua
+++ b/lua/src/p0003.lua
@@ -11,13 +11,13 @@ local prime_factors = loadlib("primes").prime_factors
 return {
     solution = function()
         local fgen = prime_factors(600851475143)
-        local f = fgen.next()
+        local f
         local answer = 0
 
-        while f do
+        repeat
             answer = f
             f = fgen.next()
-        end
+        until not f
 
         return answer
     end
diff --git a/lua/src/p0010.lua b/lua/src/p0010.lua
index f1b5b29d..315efba0 100644
--- a/lua/src/p0010.lua
+++ b/lua/src/p0010.lua
@@ -17,7 +17,7 @@ return {
         repeat
             answer = answer + tmp
             tmp = pg.next()
-        until tmp == nil
+        until not tmp
 
         return answer;
     end