diff --git a/src/spectator/formatting/match_data_value_pair.cr b/src/spectator/formatting/match_data_value_pair.cr
index 46823c3..95fa57f 100644
--- a/src/spectator/formatting/match_data_value_pair.cr
+++ b/src/spectator/formatting/match_data_value_pair.cr
@@ -1,5 +1,5 @@
 module Spectator::Formatting
-  # A single key-value pair from the `Spectator::Matchers::MatchData#value` method.
+  # A single labeled value from the `Spectator::Matchers::MatchData#value` method.
   private struct MatchDataValuePair(T)
     # Creates the pair formatter.
     def initialize(@key : Symbol, @value : T, @padding : Int32)
diff --git a/src/spectator/formatting/match_data_values.cr b/src/spectator/formatting/match_data_values.cr
index a9edac1..51b5f1e 100644
--- a/src/spectator/formatting/match_data_values.cr
+++ b/src/spectator/formatting/match_data_values.cr
@@ -1,22 +1,23 @@
 module Spectator::Formatting
   # Produces a `MatchDataValuePair` for each key-value pair
   # from `Spectator::Matchers::MatchData#values`.
-  private struct MatchDataValues(T)
+  private struct MatchDataValues
     include Enumerable(MatchDataValuePair)
 
     @max_key_length : Int32
 
     # Creates the values mapper.
-    def initialize(@values : T)
-      @max_key_length = @values.keys.map(&.to_s.size).max
+    def initialize(@values : Array(Spectator::Matchers::MatchDataLabeledValue))
+      @max_key_length = @values.map(&.label.to_s.size).max
     end
 
     # Yields pairs that can be printed to output.
     def each
-      @values.each do |key, value|
+      @values.each do |labeled_value|
+        key = labeled_value.label
         key_length = key.to_s.size
         padding = @max_key_length - key_length
-        yield MatchDataValuePair.new(key, value, padding)
+        yield MatchDataValuePair.new(key, labeled_value.value, padding)
       end
     end
   end
diff --git a/src/spectator/matchers/match_data_labeled_value.cr b/src/spectator/matchers/match_data_labeled_value.cr
index 0fc3d59..2a39095 100644
--- a/src/spectator/matchers/match_data_labeled_value.cr
+++ b/src/spectator/matchers/match_data_labeled_value.cr
@@ -1,6 +1,6 @@
 module Spectator::Matchers
   # A value from match data with a label.
-  private struct MatchDataLabeledValue
+  struct MatchDataLabeledValue
     # Label tied to the value.
     # This annotates what the value is.
     getter label : Symbol
diff --git a/src/spectator/matchers/negatable_match_data_value.cr b/src/spectator/matchers/negatable_match_data_value.cr
index ac764fe..aef6e66 100644
--- a/src/spectator/matchers/negatable_match_data_value.cr
+++ b/src/spectator/matchers/negatable_match_data_value.cr
@@ -3,7 +3,7 @@ require "./match_data_value"
 module Spectator::Matchers
   # Wraps an expected value that can be negated.
   # This is used when a matcher is negated.
-  private class NegatableMatchDataValue(T) < MatchDataValue
+  private struct NegatableMatchDataValue(T) < MatchDataValue
     # Negatable value.
     getter value