diff --git a/src/dodb/storage/stacked.cr b/src/dodb/storage/stacked.cr
index 6f20256..8a39dfc 100644
--- a/src/dodb/storage/stacked.cr
+++ b/src/dodb/storage/stacked.cr
@@ -37,7 +37,7 @@ class DODB::Storage::Stacked(V) < DODB::Storage::Cached(V)
 	property stack : FIFO(Int32)
 
 	# Initializes the `StackedDataBase` with a maximum number of entries in the cache.
-	def initialize(@directory_name : String, max_entries : UInt32 = 100_000)
+	def initialize(@directory_name : String, max_entries : UInt32)
 		@stack = FIFO(Int32).new max_entries
 		Dir.mkdir_p data_path
 		Dir.mkdir_p locks_directory
diff --git a/src/fifo.cr b/src/fifo.cr
index 81b7093..4b060a9 100644
--- a/src/fifo.cr
+++ b/src/fifo.cr
@@ -30,7 +30,7 @@ class FIFO(V)
 	# NOTE: `#<<(v : V)` is (almost) the only function since it's enough for the intended use, feel free to improve this.
 	# WARNING: implementation is extremely simple (3 lines) and not designed to be highly efficient.
 	def <<(v : V) : V?
-		@data.select! { |x| v != v }            # remove dups
+		@data.select! { |x| v != x }            # remove dups
 		@data.unshift v                         # push on top of the stack
 		@data.pop if @data.size > @max_entries  # remove least recently used entry if `@data` is too big
 	end