diff --git a/src/spectator/dsl/groups.cr b/src/spectator/dsl/groups.cr
index 2b1519c..535a842 100644
--- a/src/spectator/dsl/groups.cr
+++ b/src/spectator/dsl/groups.cr
@@ -45,7 +45,7 @@ module Spectator::DSL
             metadata
           )
 
-          \{{block.body}}
+          \{{block.body if block}}
 
           ::Spectator::DSL::Builder.end_group
         end
@@ -136,14 +136,6 @@ module Spectator::DSL
           {{collection}}
         end
 
-        {% if block.args.size == 1 %}
-          let({{block.args.first}}) do |example|
-            example.group.as(::Spectator::ExampleGroupIteration(typeof(Group%group.%collection.first))).item
-          end
-        {% elsif block.args.size > 1 %}
-          {% raise "Expected 1 argument for 'sample' block, but got #{block.args.size}" %}
-        {% end %}
-
         ::Spectator::DSL::Builder.start_iterative_group(
           %collection,
           {{collection.stringify}},
@@ -152,7 +144,17 @@ module Spectator::DSL
           metadata
         )
 
-        {{block.body}}
+        {% if block %}
+          {% if block.args.size == 1 %}
+            let({{block.args.first}}) do |example|
+              example.group.as(::Spectator::ExampleGroupIteration(typeof(Group%group.%collection.first))).item
+            end
+          {% elsif block.args.size > 1 %}
+            {% raise "Expected 1 argument for 'sample' block, but got #{block.args.size}" %}
+          {% end %}
+
+          {{block.body}}
+        {% end %}
 
         ::Spectator::DSL::Builder.end_group
       end
diff --git a/src/spectator/dsl/memoize.cr b/src/spectator/dsl/memoize.cr
index 0e9ab22..6ba3c9d 100644
--- a/src/spectator/dsl/memoize.cr
+++ b/src/spectator/dsl/memoize.cr
@@ -9,9 +9,9 @@ module Spectator::DSL
     # The block is evaluated only on the first time the getter is used
     # and the return value is saved for subsequent calls.
     macro let(name, &block)
-      {% raise "Block required for 'let'" unless block %}
-      {% raise "Cannot use 'let' inside of a test block" if @def %}
-      {% raise "Block argument count for 'let' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'let'" unless block %}
+      {% raise "Expected zero or one arguments for 'let', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'let' inside of an example block" if @def %}
       {% raise "Cannot use '#{name.id}' for 'let'" if ::Spectator::DSL::RESERVED_KEYWORDS.includes?(name.id.symbolize) %}
 
       @%value = ::Spectator::LazyWrapper.new
@@ -31,9 +31,9 @@ module Spectator::DSL
     # The block is evaluated once before the example runs
     # and the return value is saved.
     macro let!(name, &block)
-      {% raise "Block required for 'let!'" unless block %}
-      {% raise "Cannot use 'let!' inside of a test block" if @def %}
-      {% raise "Block argument count for 'let!' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'let!'" unless block %}
+      {% raise "Expected zero or one arguments for 'let!', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'let!' inside of an example block" if @def %}
       {% raise "Cannot use '#{name.id}' for 'let!'" if ::Spectator::DSL::RESERVED_KEYWORDS.includes?(name.id.symbolize) %}
 
       let({{name}}) {{block}}
@@ -45,9 +45,9 @@ module Spectator::DSL
     # The block is evaluated only the first time the subject is referenced
     # and the return value is saved for subsequent calls.
     macro subject(&block)
-      {% raise "Block required for 'subject'" unless block %}
-      {% raise "Cannot use 'subject' inside of a test block" if @def %}
-      {% raise "Block argument count for 'subject' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'subject'" unless block %}
+      {% raise "Expected zero or one arguments for 'let!', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'subject' inside of an example block" if @def %}
 
       let(subject) {{block}}
     end
@@ -58,9 +58,9 @@ module Spectator::DSL
     # The block is evaluated only the first time the subject is referenced
     # and the return value is saved for subsequent calls.
     macro subject(name, &block)
-      {% raise "Block required for 'subject'" unless block %}
-      {% raise "Cannot use 'subject' inside of a test block" if @def %}
-      {% raise "Block argument count for 'subject' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'subject'" unless block %}
+      {% raise "Expected zero or one arguments for 'subject', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'subject' inside of an example block" if @def %}
       {% raise "Cannot use '#{name.id}' for 'subject'" if ::Spectator::DSL::RESERVED_KEYWORDS.includes?(name.id.symbolize) %}
 
       let({{name.id}}) {{block}}
@@ -77,9 +77,9 @@ module Spectator::DSL
     # The block is evaluated once before the example runs
     # and the return value is saved for subsequent calls.
     macro subject!(&block)
-      {% raise "Block required for 'subject!'" unless block %}
-      {% raise "Cannot use 'subject!' inside of a test block" if @def %}
-      {% raise "Block argument count for 'subject!' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'subject'" unless block %}
+      {% raise "Expected zero or one arguments for 'subject!', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'subject!' inside of an example block" if @def %}
 
       let!(subject) {{block}}
     end
@@ -90,9 +90,9 @@ module Spectator::DSL
     # The block is evaluated once before the example runs
     # and the return value is saved for subsequent calls.
     macro subject!(name, &block)
-      {% raise "Block required for 'subject!'" unless block %}
-      {% raise "Cannot use 'subject!' inside of a test block" if @def %}
-      {% raise "Block argument count for 'subject!' must be 0..1" if block.args.size > 1 %}
+      {% raise "Missing block for 'subject'" unless block %}
+      {% raise "Expected zero or one arguments for 'subject!', but got #{block.args.size}" if block.args.size > 1 %}
+      {% raise "Cannot use 'subject!' inside of an example block" if @def %}
       {% raise "Cannot use '#{name.id}' for 'subject!'" if ::Spectator::DSL::RESERVED_KEYWORDS.includes?(name.id.symbolize) %}
 
       let!({{name.id}}) {{block}}