diff --git a/Dockerfile b/Dockerfile
index c7cbcfd5..88a94650 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -1,4 +1,4 @@
-FROM crystallang/crystal:1.0.0
+FROM crystallang/crystal:1.6.0
 
 ARG sqlite_version=3110000
 ARG sqlite_version_year=2016
diff --git a/shard.yml b/shard.yml
index b7dfb8c7..619383ca 100644
--- a/shard.yml
+++ b/shard.yml
@@ -30,4 +30,4 @@ development_dependencies:
 
   ameba:
     github: crystal-ameba/ameba
-    version: ~> 0.13.0
+    version: ~> 1.3.1
diff --git a/spec/adapter/adapters_spec.cr b/spec/adapter/adapters_spec.cr
index 3b4cc5c2..41c70290 100644
--- a/spec/adapter/adapters_spec.cr
+++ b/spec/adapter/adapters_spec.cr
@@ -15,9 +15,21 @@ describe Granite::Connections do
     it "should allow connections to be be saved and looked up" do
       Granite::Connections.registered_connections.size.should eq 3
 
-      Granite::Connections["mysql"].not_nil!.url.should eq ENV["MYSQL_DATABASE_URL"]
-      Granite::Connections["pg"].not_nil!.url.should eq ENV["PG_DATABASE_URL"]
-      Granite::Connections["sqlite"].not_nil!.url.should eq ENV["SQLITE_DATABASE_URL"]
+      if connection = Granite::Connections["mysql"]
+        connection.url.should eq ENV["MYSQL_DATABASE_URL"]
+      else
+        connection.should_not be_falsey
+      end
+      if connection = Granite::Connections["pg"]
+        connection.url.should eq ENV["PG_DATABASE_URL"]
+      else
+        connection.should_not be_falsey
+      end
+      if connection = Granite::Connections["sqlite"]
+        connection.url.should eq ENV["SQLITE_DATABASE_URL"]
+      else
+        connection.should_not be_falsey
+      end
     end
 
     it "should disallow multiple connections with the same name" do
diff --git a/spec/granite/associations/has_many_spec.cr b/spec/granite/associations/has_many_spec.cr
index 161f30af..3fb7ebe9 100644
--- a/spec/granite/associations/has_many_spec.cr
+++ b/spec/granite/associations/has_many_spec.cr
@@ -68,9 +68,13 @@ describe "has_many" do
       klass3.teacher = teacher
       klass3.save
 
-      klass = teacher.klasses.find_by(name: "Test class with different name").not_nil!
-      klass.id.should eq klass3.id
-      klass.name.should eq "Test class with different name"
+      klass = teacher.klasses.find_by(name: "Test class with different name")
+      if klass
+        klass.id.should eq klass3.id
+        klass.name.should eq "Test class with different name"
+      else
+        klass.should_not be_nil
+      end
     end
 
     it "#find_by!" do
@@ -93,7 +97,7 @@ describe "has_many" do
       klass3.teacher = teacher
       klass3.save
 
-      klass = teacher.klasses.find_by!(name: "Test class with different name").not_nil!
+      klass = teacher.klasses.find_by!(name: "Test class with different name")
       klass.id.should eq klass3.id
       klass.name.should eq "Test class with different name"
 
@@ -125,9 +129,13 @@ describe "has_many" do
       klass3.teacher = teacher
       klass3.save
 
-      klass = teacher.klasses.find(klass1.id).not_nil!
-      klass.id.should eq klass1.id
-      klass.name.should eq "Test class X"
+      klass = teacher.klasses.find(klass1.id)
+      if klass
+        klass.id.should eq klass1.id
+        klass.name.should eq "Test class X"
+      else
+        klass.should_not be_nil
+      end
     end
 
     it "#find!" do
@@ -150,7 +158,7 @@ describe "has_many" do
       klass3.teacher = teacher
       klass3.save
 
-      klass = teacher.klasses.find!(klass1.id).not_nil!
+      klass = teacher.klasses.find!(klass1.id)
       klass.id.should eq klass1.id
       klass.name.should eq "Test class X"
 
diff --git a/spec/granite/associations/has_many_through_spec.cr b/spec/granite/associations/has_many_through_spec.cr
index 36bca32f..fda28ea0 100644
--- a/spec/granite/associations/has_many_through_spec.cr
+++ b/spec/granite/associations/has_many_through_spec.cr
@@ -37,9 +37,9 @@ describe "has_many, through:" do
     enrollment3.student = unrelated_student
     enrollment3.save
 
-    student.klasses.map(&.id).compact.sort.should eq [klass1.id, klass2.id].compact.sort
+    student.klasses.compact_map(&.id).sort!.should eq [klass1.id, klass2.id].compact.sort!
 
-    klass2.students.map(&.id).compact.sort.should eq [student.id, unrelated_student.id].compact.sort
+    klass2.students.compact_map(&.id).sort!.should eq [student.id, unrelated_student.id].compact.sort!
   end
 
   context "querying association" do
@@ -91,9 +91,13 @@ describe "has_many, through:" do
       enrollment3.student = student
       enrollment3.save
 
-      klass = student.klasses.find_by(name: "Test class with different name").not_nil!
-      klass.id.should eq klass3.id
-      klass.name.should eq "Test class with different name"
+      klass = student.klasses.find_by(name: "Test class with different name")
+      if klass
+        klass.id.should eq klass3.id
+        klass.name.should eq "Test class with different name"
+      else
+        klass.should_not be_nil
+      end
     end
 
     it "#find_by!" do
@@ -118,7 +122,7 @@ describe "has_many, through:" do
       enrollment3.student = student
       enrollment3.save
 
-      klass = student.klasses.find_by!(name: "Test class with different name").not_nil!
+      klass = student.klasses.find_by!(name: "Test class with different name")
       klass.id.should eq klass3.id
       klass.name.should eq "Test class with different name"
 
@@ -152,9 +156,13 @@ describe "has_many, through:" do
       enrollment3.student = student
       enrollment3.save
 
-      klass = student.klasses.find(klass1.id).not_nil!
-      klass.id.should eq klass1.id
-      klass.name.should eq "Test class X"
+      klass = student.klasses.find(klass1.id)
+      if klass
+        klass.id.should eq klass1.id
+        klass.name.should eq "Test class X"
+      else
+        klass.should_not be_nil
+      end
     end
 
     it "#find!" do
@@ -179,7 +187,7 @@ describe "has_many, through:" do
       enrollment3.student = student
       enrollment3.save
 
-      klass = student.klasses.find!(klass1.id).not_nil!
+      klass = student.klasses.find!(klass1.id)
       klass.id.should eq klass1.id
       klass.name.should eq "Test class X"
 
diff --git a/spec/granite/querying/all_spec.cr b/spec/granite/querying/all_spec.cr
index c8176708..71c58086 100644
--- a/spec/granite/querying/all_spec.cr
+++ b/spec/granite/querying/all_spec.cr
@@ -9,7 +9,7 @@ describe "#all" do
 
     all = Parent.all
     all.size.should eq model_ids.size
-    all.map(&.id).compact.sort.should eq model_ids.compact
+    all.compact_map(&.id).sort!.should eq model_ids.compact
   end
 
   # TODO Fails under MySQL
diff --git a/spec/granite/querying/find_by_spec.cr b/spec/granite/querying/find_by_spec.cr
index e4f10a16..c77e6d64 100644
--- a/spec/granite/querying/find_by_spec.cr
+++ b/spec/granite/querying/find_by_spec.cr
@@ -9,7 +9,11 @@ describe "#find_by, #find_by!" do
     model.save.should be_true
 
     found = Parent.find_by(name: name)
-    found.not_nil!.id.should eq model.id
+    if pa = found
+      pa.id.should eq model.id
+    else
+      pa.should_not be_nil
+    end
 
     found = Parent.find_by!(name: name)
     found.should be_a(Parent)
@@ -23,7 +27,12 @@ describe "#find_by, #find_by!" do
 
     expected = Review.create(name: "review3", upvotes: 10.to_i64)
 
-    Review.find_by(name: "review3", upvotes: 10).not_nil!.id.should eq expected.id
+    r = Review.find_by(name: "review3", upvotes: 10)
+    if r
+      r.id.should eq expected.id
+    else
+      r.should_not be_nil
+    end
 
     expect_raises(Granite::Querying::NotFound, /No .*Review.* found where name = review1 and upvotes = 20/) do
       Review.find_by!(name: "review1", upvotes: 20)
@@ -37,7 +46,11 @@ describe "#find_by, #find_by!" do
     model.save.should be_true
 
     found = Student.find_by(name: nil)
-    found.not_nil!.id.should eq model.id
+    if stu = found
+      stu.id.should eq model.id
+    else
+      stu.should_not be_nil
+    end
 
     found = Student.find_by!(name: nil)
     found.should be_a(Student)
@@ -52,7 +65,11 @@ describe "#find_by, #find_by!" do
     model.save.should be_true
 
     found = ReservedWord.find_by(all: value)
-    found.not_nil!.id.should eq model.id
+    if rw = found
+      rw.id.should eq model.id
+    else
+      rw.should_not be_nil
+    end
 
     found = ReservedWord.find_by!(all: value)
     found.id.should eq model.id
@@ -66,7 +83,11 @@ describe "#find_by, #find_by!" do
     model.save.should be_true
 
     found = Parent.find_by({"name" => name})
-    found.not_nil!.id.should eq model.id
+    if pa = found
+      pa.id.should eq model.id
+    else
+      pa.should_not be_nil
+    end
 
     found = Parent.find_by!({"name" => name})
     found.should be_a(Parent)
diff --git a/spec/granite/querying/find_each_spec.cr b/spec/granite/querying/find_each_spec.cr
index 5c6c5c9d..28f1e9b6 100644
--- a/spec/granite/querying/find_each_spec.cr
+++ b/spec/granite/querying/find_each_spec.cr
@@ -4,7 +4,7 @@ describe "#find_each" do
   it "finds all the records" do
     Parent.clear
     model_ids = (0...100).map do |i|
-      Parent.new(name: "role_#{i}").tap { |r| r.save }
+      Parent.new(name: "role_#{i}").tap(&.save)
     end.map(&.id)
 
     found_roles = [] of Int64 | Nil
@@ -12,7 +12,7 @@ describe "#find_each" do
       found_roles << model.id
     end
 
-    found_roles.compact.sort.should eq model_ids.compact
+    found_roles.compact.sort!.should eq model_ids.compact
   end
 
   it "doesnt yield when no records are found" do
@@ -38,7 +38,7 @@ describe "#find_each" do
       found_models << model.id
     end
 
-    found_models.compact.sort.should eq created_models.compact
+    found_models.compact.sort!.should eq created_models.compact
   end
 
   it "doesnt obliterate a parameterized query" do
diff --git a/spec/granite/querying/find_in_batches.cr b/spec/granite/querying/find_in_batches.cr
index ac487975..895339e5 100644
--- a/spec/granite/querying/find_in_batches.cr
+++ b/spec/granite/querying/find_in_batches.cr
@@ -12,7 +12,7 @@ describe "#find_in_batches" do
       batch.size.should eq 10
     end
 
-    found_models.compact.sort.should eq model_ids.compact
+    found_models.compact.sort!.should eq model_ids.compact
   end
 
   it "doesnt yield when no records are found" do
@@ -56,7 +56,7 @@ describe "#find_in_batches" do
       end
     end
 
-    found_models.compact.sort.should eq created_models.compact
+    found_models.compact.sort!.should eq created_models.compact
   end
 
   it "doesnt obliterate a parameterized query" do
@@ -67,7 +67,7 @@ describe "#find_in_batches" do
     looking_for_ids = created_models[0...5]
 
     Parent.find_in_batches("WHERE id IN(#{looking_for_ids.join(",")})") do |batch|
-      batch.map(&.id).compact.should eq looking_for_ids
+      batch.compact_map(&.id).should eq looking_for_ids
     end
   end
 end
diff --git a/spec/granite/querying/find_spec.cr b/spec/granite/querying/find_spec.cr
index 6d94f5f3..fd70dc58 100644
--- a/spec/granite/querying/find_spec.cr
+++ b/spec/granite/querying/find_spec.cr
@@ -8,7 +8,7 @@ describe "#find, #find!" do
 
     found = Parent.find model.id
     found.should_not be_nil
-    found.not_nil!.id.should eq model.id
+    found && (found.id.should eq model.id)
 
     found = Parent.find! model.id
     found.id.should eq model.id
diff --git a/spec/granite/querying/first_spec.cr b/spec/granite/querying/first_spec.cr
index 2549e181..b9251889 100644
--- a/spec/granite/querying/first_spec.cr
+++ b/spec/granite/querying/first_spec.cr
@@ -14,7 +14,11 @@ describe "#first, #first!" do
     end
 
     found = Parent.first
-    found.not_nil!.id.should eq first.id
+    if pa = found
+      pa.id.should eq first.id
+    else
+      pa.should_not be_nil
+    end
 
     found = Parent.first!
     found.id.should eq first.id
@@ -33,7 +37,11 @@ describe "#first, #first!" do
     end
 
     found = Parent.first("ORDER BY id DESC")
-    found.not_nil!.id.should eq second.id
+    if pa = found
+      found.id.should eq second.id
+    else
+      pa.should_not be_nil
+    end
 
     found = Parent.first!("ORDER BY id DESC")
     found.id.should eq second.id
diff --git a/spec/granite/transactions/create_spec.cr b/spec/granite/transactions/create_spec.cr
index 832daaca..975e1bda 100644
--- a/spec/granite/transactions/create_spec.cr
+++ b/spec/granite/transactions/create_spec.cr
@@ -13,20 +13,19 @@ describe "#create" do
   end
 
   it "doesn't have a race condition on IDs" do
+    n = 1000
+    ids = Array(Int64).new(n)
     channel = Channel(Int64).new
 
-    2.times do
+    n.times do
       spawn do
         parent = Parent.new(name: "Test Parent")
         parent.save
-        channel.send(parent.id.not_nil!)
+        (id = parent.id) && channel.send(id)
       end
     end
-
-    id1 = channel.receive
-    id2 = channel.receive
-
-    id1.should_not eq id2
+    n.times { ids << channel.receive }
+    ids.uniq!.size.should eq n
   end
 
   describe "with a custom primary key" do
diff --git a/spec/granite/transactions/import_spec.cr b/spec/granite/transactions/import_spec.cr
index 55e44e62..81271104 100644
--- a/spec/granite/transactions/import_spec.cr
+++ b/spec/granite/transactions/import_spec.cr
@@ -38,7 +38,7 @@ describe "#import" do
 
         reviews = Review.all("WHERE name LIKE ?", ["ImportReview%"])
         reviews.size.should eq 4
-        reviews.none? { |r| r.published }.should be_true
+        reviews.none?(&.published).should be_true
         reviews.all? { |r| r.upvotes == 0 }.should be_true
 
         reviews.each { |r| r.published = true; r.upvotes = 1.to_i64 }
@@ -48,7 +48,7 @@ describe "#import" do
         reviews = Review.all("WHERE name LIKE ?", ["ImportReview%"])
 
         reviews.size.should eq 4
-        reviews.all? { |r| r.published }.should be_true
+        reviews.all?(&.published).should be_true
         reviews.all? { |r| r.upvotes == 1 }.should be_true
       end
     end
@@ -132,7 +132,7 @@ describe "#import" do
         schools.size.should eq 4
         schools.all? { |s| s.name == "ImportExistingSchool" }.should be_true
 
-        schools.each { |s| s.name = "ImportExistingSchoolEdited" }
+        schools.each(&.name=("ImportExistingSchoolEdited"))
 
         School.import(schools, update_on_duplicate: true, columns: ["name"])
 
diff --git a/src/adapter/pg.cr b/src/adapter/pg.cr
index 5d017d7d..5624d77a 100644
--- a/src/adapter/pg.cr
+++ b/src/adapter/pg.cr
@@ -44,7 +44,7 @@ class Granite::Adapter::Pg < Granite::Adapter::Base
       stmt << "INSERT INTO #{quote(table_name)} ("
       stmt << fields.map { |name| "#{quote(name)}" }.join(", ")
       stmt << ") VALUES ("
-      stmt << fields.map { |name| "$#{fields.index(name).not_nil! + 1}" }.join(", ")
+      stmt << position_str(fields.size)
       stmt << ")"
 
       stmt << " RETURNING #{quote(lastval)}" if lastval
@@ -116,7 +116,7 @@ class Granite::Adapter::Pg < Granite::Adapter::Base
   def update(table_name : String, primary_name : String, fields, params)
     statement = String.build do |stmt|
       stmt << "UPDATE #{quote(table_name)} SET "
-      stmt << fields.map { |name| "#{quote(name)}=$#{fields.index(name).not_nil! + 1}" }.join(", ")
+      stmt << fields.map_with_index { |name, i| "#{quote(name)}=$#{i + 1}" }.join(", ")
       stmt << " WHERE #{quote(primary_name)}=$#{fields.size + 1}"
     end
 
@@ -153,4 +153,15 @@ class Granite::Adapter::Pg < Granite::Adapter::Base
 
     clause
   end
+
+  private def position_str(n : Int32) : String
+    i = 1
+    String.build do |str|
+      while i <= n
+        str << "$" << i
+        i += 1
+        str << ", " if i <= n
+      end
+    end
+  end
 end
diff --git a/src/granite/columns.cr b/src/granite/columns.cr
index 348a08ac..b299e171 100644
--- a/src/granite/columns.cr
+++ b/src/granite/columns.cr
@@ -9,7 +9,7 @@ module Granite::Columns
     # All fields
     def fields : Array(String)
       {% begin %}
-        {% columns = @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) }.map(&.name.stringify) %}
+        {% columns = @type.instance_vars.select(&.annotation(Granite::Column)).map(&.name.stringify) %}
         {{columns.empty? ? "[] of String".id : columns}}
       {% end %}
     end
@@ -37,7 +37,7 @@ module Granite::Columns
     {% begin %}
       result.column_names.each do |col|
         case col
-        {% for column in @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) } %}
+        {% for column in @type.instance_vars.select(&.annotation(Granite::Column)) %}
           {% ann = column.annotation(Granite::Column) %}
           when {{column.name.stringify}}
             @{{column.id}} = {% if ann[:converter] %}
@@ -109,9 +109,9 @@ module Granite::Columns
   end
 
   def to_h
-    fields = {{"Hash(String, Union(#{@type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) }.map(&.type.id).splat})).new".id}}
+    fields = {{"Hash(String, Union(#{@type.instance_vars.select(&.annotation(Granite::Column)).map(&.type.id).splat})).new".id}}
 
-    {% for column in @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) } %}
+    {% for column in @type.instance_vars.select(&.annotation(Granite::Column)) %}
         {% if column.type.id == Time.id %}
           fields["{{column.name}}"] = {{column.name.id}}.try(&.in(Granite.settings.default_timezone).to_s(Granite::DATETIME_FORMAT))
         {% elsif column.type.id == Slice.id %}
@@ -148,7 +148,7 @@ module Granite::Columns
   def read_attribute(attribute_name : Symbol | String) : Type
     {% begin %}
       case attribute_name.to_s
-      {% for column in @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) } %}
+      {% for column in @type.instance_vars.select(&.annotation(Granite::Column)) %}
         when "{{ column.name }}" then @{{ column.name.id }}
       {% end %}
       else
diff --git a/src/granite/query/executors/value.cr b/src/granite/query/executors/value.cr
index 501f0524..2e03f1df 100644
--- a/src/granite/query/executors/value.cr
+++ b/src/granite/query/executors/value.cr
@@ -10,10 +10,12 @@ module Granite::Query::Executor
       # db.scalar raises when a query returns 0 results, so I'm using query_one?
       # https://github.com/crystal-lang/crystal-db/blob/7d30e9f50e478cb6404d16d2ce91e639b6f9c476/src/db/statement.cr#L18
 
-      raise "No default provided" if @default.nil?
-
-      Model.adapter.open do |db|
-        db.query_one?(@sql, args: @args, as: Scalar) || @default.not_nil!
+      if @default.nil?
+        raise "No default provided"
+      else
+        Model.adapter.open do |db|
+          db.query_one?(@sql, args: @args, as: Scalar) || @default
+        end
       end
     end
 
diff --git a/src/granite/querying.cr b/src/granite/querying.cr
index 113a2e37..f019d5a5 100644
--- a/src/granite/querying.cr
+++ b/src/granite/querying.cr
@@ -87,7 +87,7 @@ module Granite::Querying
 
     loop do
       results = all "#{clause} LIMIT ? OFFSET ?", params + [limit, offset]
-      break unless results.any?
+      break if results.empty?
       yield results
       offset += limit
     end
@@ -115,7 +115,7 @@ module Granite::Querying
   end
 
   def exec(clause = "")
-    adapter.open { |db| db.exec(clause) }
+    adapter.open(&.exec(clause))
   end
 
   def query(clause = "", params = [] of Granite::Columns::Type, &block)
diff --git a/src/granite/transactions.cr b/src/granite/transactions.cr
index 57945359..e882a8ea 100644
--- a/src/granite/transactions.cr
+++ b/src/granite/transactions.cr
@@ -24,7 +24,7 @@ module Granite::Transactions
     def create!(args : Granite::ModelArgs)
       instance = create(args)
 
-      if instance.errors.any?
+      if !instance.errors.empty?
         raise Granite::RecordNotSaved.new(self.name, instance)
       end
 
@@ -78,13 +78,13 @@ module Granite::Transactions
   end
 
   def set_timestamps(*, to time = Time.local(Granite.settings.default_timezone), mode = :create)
-    {% if @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) }.map(&.name.stringify).includes? "created_at" %}
+    {% if @type.instance_vars.select(&.annotation(Granite::Column)).map(&.name.stringify).includes? "created_at" %}
       if mode == :create
         @created_at = time.at_beginning_of_second
       end
     {% end %}
 
-    {% if @type.instance_vars.select { |ivar| ivar.annotation(Granite::Column) }.map(&.name.stringify).includes? "updated_at" %}
+    {% if @type.instance_vars.select(&.annotation(Granite::Column)).map(&.name.stringify).includes? "updated_at" %}
       @updated_at = time.at_beginning_of_second
     {% end %}
   end