diff --git a/src/crystal/system/unix/getrandom.cr b/src/crystal/system/unix/getrandom.cr
index 7be835ff5ab9..229716a3d846 100644
--- a/src/crystal/system/unix/getrandom.cr
+++ b/src/crystal/system/unix/getrandom.cr
@@ -62,9 +62,9 @@ module Crystal::System::Random
     init unless @@initialized
 
     if @@getrandom_available
-      buf = uninitialized UInt8[1]
-      getrandom(buf.to_slice)
-      buf.unsafe_as(UInt8)
+      buf = uninitialized UInt8
+      getrandom(pointerof(buf).to_slice(1))
+      buf
     elsif urandom = @@urandom
       urandom.read_byte.not_nil!
     else
diff --git a/src/crystal/system/wasi/random.cr b/src/crystal/system/wasi/random.cr
index 72649fac3e7c..3b50ff7fdf44 100644
--- a/src/crystal/system/wasi/random.cr
+++ b/src/crystal/system/wasi/random.cr
@@ -7,8 +7,8 @@ module Crystal::System::Random
   end
 
   def self.next_u : UInt8
-    buf = uninitialized UInt8[1]
-    random_bytes(buf.to_slice)
-    buf.unsafe_as(UInt8)
+    buf = uninitialized UInt8
+    random_bytes(pointerof(buf).to_slice(1))
+    buf
   end
 end
diff --git a/src/crystal/system/win32/random.cr b/src/crystal/system/win32/random.cr
index 03c54fa8aa40..faec72ca9b57 100644
--- a/src/crystal/system/win32/random.cr
+++ b/src/crystal/system/win32/random.cr
@@ -8,8 +8,8 @@ module Crystal::System::Random
   end
 
   def self.next_u : UInt8
-    buf = uninitialized UInt8[1]
-    random_bytes(buf.to_slice)
-    buf.unsafe_as(UInt8)
+    buf = uninitialized UInt8
+    random_bytes(pointerof(buf).to_slice(1))
+    buf
   end
 end