diff --git a/lib/std/math/math_random.c3 b/lib/std/math/math_random.c3
index 0b2eaa9fc..f5d2c4d4d 100644
--- a/lib/std/math/math_random.c3
+++ b/lib/std/math/math_random.c3
@@ -1,18 +1,15 @@
+/**
+ * Randoms:
+ * General usage -
+ * 1. Create a Random (see std/math/random for various alternatives), or pick DefaultRandom
+ * 2. Define it `DefaultRandom my_random;`
+ * 3. Seed it: `random::seed(&my_random, some_seed);` or `rand::seed_entropy(&my_random);`
+ * 4. Use it with the functions in random: `float random_float = random::next_float(&my_random);`
+ *
+ * For just a simple integer between 0 and n (not including n), you can use `rand(n)`.
+ **/
 module std::math::random;
 
-interface Random
-{
-	fn void set_seed(char[] input);
-	fn char next_byte();
-	fn ushort next_short();
-	fn uint next_int();
-	fn ulong next_long();
-	fn uint128 next_int128();
-	fn void next_bytes(char[] buffer);
-}
-
-macro bool is_random(random) => $assignable(random, Random*);
-
 /**
  * @require is_random(random)
  **/
@@ -21,12 +18,19 @@ macro void seed(random, seed)
 	random.set_seed(@as_char_view(seed));
 }
 
+/**
+ * Seed the random with some best effort entropy.
+ *
+ * @require is_random(random)
+ **/
 macro void seed_entropy(random)
 {
 	random.set_seed(&&entropy());
 }
 
 /**
+ * Get the next value between 0 and max (not including max).
+ *
  * @require is_random(random)
  **/
 macro int next(random, int max)
@@ -34,6 +38,11 @@ macro int next(random, int max)
 	return (int)(next_double(random) * max);
 }
 
+def DefaultRandom = Sfc64Random;
+
+/**
+ * Get a default random value between 0 and max (not including max)
+ **/
 fn int rand(int max) @builtin
 {
 	tlocal Sfc64Random default_random;
@@ -45,15 +54,20 @@ fn int rand(int max) @builtin
 	}
 	return next(&default_random, max);
 }
+
 /**
+ * Get 'true' or 'false'
+ *
  * @require is_random(random)
  **/
 macro bool next_bool(random)
 {
-	return random.next_byte() & 1;
+	return (bool)(random.next_byte() & 1);
 }
 
 /**
+ * Get a float between 0 and 1.0, not including 1.0.
+ *
  * @require is_random(random)
  **/
 macro float next_float(random)
@@ -63,6 +77,8 @@ macro float next_float(random)
 }
 
 /**
+ * Get a double between 0 and 1.0, not including 1.0.
+ *
  * @require is_random(random)
  **/
 macro double next_double(random)
@@ -71,6 +87,9 @@ macro double next_double(random)
 	return val * 0x1.0p-53;
 }
 
+// True if the value is a Random.
+macro bool is_random(random) => $assignable(random, Random);
+
 macro uint128 @long_to_int128(#function) => (uint128)#function << 64 + #function;
 macro ulong @int_to_long(#function) => (ulong)#function << 32 + #function;
 macro uint @short_to_int(#function) => (uint)#function << 16 + #function;
@@ -95,3 +114,16 @@ macro @random_value_to_bytes(#function, char[] bytes)
 	}
 	unreachable();
 }
+
+// This is the interface to implement for Random implementations, usually
+// it is not invoked directly.
+interface Random
+{
+	fn void set_seed(char[] input);
+	fn char next_byte();
+	fn ushort next_short();
+	fn uint next_int();
+	fn ulong next_long();
+	fn uint128 next_int128();
+	fn void next_bytes(char[] buffer);
+}
diff --git a/releasenotes.md b/releasenotes.md
index 82e5d52e3..fd9dbd7e4 100644
--- a/releasenotes.md
+++ b/releasenotes.md
@@ -13,6 +13,7 @@
 
 ### Fixes
 - Broken WASM library code.
+- Regression: Invalid is_random implementation due to changes in 0.6.
 
 ### Stdlib changes
 None
diff --git a/test/unit/stdlib/math/random.c3 b/test/unit/stdlib/math/random.c3
new file mode 100644
index 000000000..884ec04e0
--- /dev/null
+++ b/test/unit/stdlib/math/random.c3
@@ -0,0 +1,35 @@
+module std::math::random @test;
+import std::math;
+
+fn void test_regular_random()
+{
+	for (int i = 0; i < 100; i++) assert(rand(45) < 45 && rand(45) >= 0);
+}
+
+fn void test_next_bool()
+{
+	DefaultRandom rand;
+	random::seed_entropy(&rand);
+	for (int i = 0; i < 100; i++) random::next_bool(&rand);
+}
+
+fn void test_next()
+{
+	DefaultRandom rand;
+	random::seed_entropy(&rand);
+	for (int i = 0; i < 100; i++) assert(random::next(&rand, 100) < 100.0 && random::next(&rand, 100) >= 0);
+}
+
+fn void test_next_double()
+{
+	DefaultRandom rand;
+	random::seed_entropy(&rand);
+	for (int i = 0; i < 100; i++) assert(random::next_double(&rand) < 1.0 && random::next_double(&rand) >= 0);
+}
+
+fn void test_next_float()
+{
+	DefaultRandom rand;
+	random::seed_entropy(&rand);
+	for (int i = 0; i < 100; i++) assert(random::next_float(&rand) < 1.0 && random::next_float(&rand) >= 0);
+}
\ No newline at end of file