diff --git a/lib/std/mem/Allocator.zig b/lib/std/mem/Allocator.zig
index 0d4ab9141f3a8e9e47fa591c62b65847daa092da..8aea197d6ae8d019094ca1320fa9e625bd089cc4 100644
--- a/lib/std/mem/Allocator.zig
+++ b/lib/std/mem/Allocator.zig
@@ -301,8 +301,9 @@ pub fn reallocAdvanced(
     return mem.bytesAsSlice(T, new_bytes);
 }
 
-/// Free an array allocated with `alloc`. To free a single item,
-/// see `destroy`.
+/// Free an array allocated with `alloc`.
+/// If memory has length 0, free is a no-op.
+/// To free a single item, see `destroy`.
 pub fn free(self: Allocator, memory: anytype) void {
     const Slice = @typeInfo(@TypeOf(memory)).pointer;
     const bytes = mem.sliceAsBytes(memory);