diff --git a/spec/avram/float_criteria_spec.cr b/spec/avram/float_criteria_spec.cr
new file mode 100644
index 000000000..9a2dc145f
--- /dev/null
+++ b/spec/avram/float_criteria_spec.cr
@@ -0,0 +1,33 @@
+require "../spec_helper"
+
+private class QueryMe < BaseModel
+  COLUMN_SQL = "purchases.id, purchases.created_at, purchases.updated_at, purchases.amount"
+
+  table purchases do
+    column amount : Float64
+  end
+end
+
+describe Float64::Lucky::Criteria do
+  describe "abs" do
+    it "uses ABS" do
+      amount.abs.eq(39.99).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM purchases WHERE ABS(purchases.amount) = $1", "39.99"]
+    end
+  end
+
+  describe "ceil" do
+    it "uses CEIL" do
+      amount.ceil.eq(40.0).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM purchases WHERE CEIL(purchases.amount) = $1", "40.0"]
+    end
+  end
+
+  describe "floor" do
+    it "uses FLOOR" do
+      amount.floor.eq(39.0).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM purchases WHERE FLOOR(purchases.amount) = $1", "39.0"]
+    end
+  end
+end
+
+private def amount
+  QueryMe::BaseQuery.new.amount
+end
diff --git a/spec/avram/integer_criteria_spec.cr b/spec/avram/integer_criteria_spec.cr
new file mode 100644
index 000000000..27396c545
--- /dev/null
+++ b/spec/avram/integer_criteria_spec.cr
@@ -0,0 +1,34 @@
+require "../spec_helper"
+
+private class QueryMe < BaseModel
+  COLUMN_SQL = "transactions.id, transactions.created_at, transactions.updated_at, transactions.small_amount, transactions.amount, transactions.big_amount"
+
+  table transactions do
+    column small_amount : Int16
+    column amount : Int32
+    column big_amount : Int64
+  end
+end
+
+# These specs handle all ints: Int16, Int32, Int64
+describe "Int::Lucky::Criteria" do
+  describe "abs" do
+    it "uses ABS" do
+      small_amount.abs.eq(4).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM transactions WHERE ABS(transactions.small_amount) = $1", "4"]
+      amount.abs.eq(400).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM transactions WHERE ABS(transactions.amount) = $1", "400"]
+      big_amount.abs.eq(40000).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM transactions WHERE ABS(transactions.big_amount) = $1", "40000"]
+    end
+  end
+end
+
+private def small_amount
+  QueryMe::BaseQuery.new.small_amount
+end
+
+private def amount
+  QueryMe::BaseQuery.new.amount
+end
+
+private def big_amount
+  QueryMe::BaseQuery.new.big_amount
+end
diff --git a/spec/avram/string_criteria_spec.cr b/spec/avram/string_criteria_spec.cr
index 25621e696..b699690da 100644
--- a/spec/avram/string_criteria_spec.cr
+++ b/spec/avram/string_criteria_spec.cr
@@ -52,6 +52,18 @@ describe String::Lucky::Criteria do
       end
     end
   end
+
+  describe "length" do
+    it "uses LENGTH" do
+      name.length.eq(4).to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM users WHERE LENGTH(users.name) = $1", "4"]
+    end
+  end
+
+  describe "reverse" do
+    it "uses REVERSE" do
+      name.reverse.eq("revir").to_sql.should eq ["SELECT #{QueryMe::COLUMN_SQL} FROM users WHERE REVERSE(users.name) = $1", "revir"]
+    end
+  end
 end
 
 private def name
diff --git a/src/avram/charms/float64_extensions.cr b/src/avram/charms/float64_extensions.cr
index a06cca6b6..ffed54e66 100644
--- a/src/avram/charms/float64_extensions.cr
+++ b/src/avram/charms/float64_extensions.cr
@@ -69,6 +69,10 @@ struct Float64
       def select_sum! : Float64
         select_sum || 0_f64
       end
+
+      define_function_criteria(abs, V)
+      define_function_criteria(ceil, V)
+      define_function_criteria(floor, V)
     end
   end
 end
diff --git a/src/avram/charms/int16_extensions.cr b/src/avram/charms/int16_extensions.cr
index a8b8f2eb0..9c48472bc 100644
--- a/src/avram/charms/int16_extensions.cr
+++ b/src/avram/charms/int16_extensions.cr
@@ -58,6 +58,8 @@ struct Int16
       def select_sum! : Int64
         select_sum || 0_i64
       end
+
+      define_function_criteria(abs, V)
     end
   end
 end
diff --git a/src/avram/charms/int32_extensions.cr b/src/avram/charms/int32_extensions.cr
index 42f8458a7..d2ca065ac 100644
--- a/src/avram/charms/int32_extensions.cr
+++ b/src/avram/charms/int32_extensions.cr
@@ -59,6 +59,8 @@ struct Int32
       def select_sum! : Int64
         select_sum || 0_i64
       end
+
+      define_function_criteria(abs, V)
     end
   end
 end
diff --git a/src/avram/charms/int64_extensions.cr b/src/avram/charms/int64_extensions.cr
index 3ae83c747..665c4f49d 100644
--- a/src/avram/charms/int64_extensions.cr
+++ b/src/avram/charms/int64_extensions.cr
@@ -57,6 +57,8 @@ struct Int64
       def select_sum! : Int64
         select_sum || 0_i64
       end
+
+      define_function_criteria(abs, V)
     end
   end
 end
diff --git a/src/avram/charms/string_extensions.cr b/src/avram/charms/string_extensions.cr
index 25fe87655..c872661b1 100644
--- a/src/avram/charms/string_extensions.cr
+++ b/src/avram/charms/string_extensions.cr
@@ -41,6 +41,8 @@ class String
       define_function_criteria(upper, V)
       define_function_criteria(lower, V)
       define_function_criteria(trim, String)
+      define_function_criteria(length, Int64)
+      define_function_criteria(reverse, String)
     end
   end
 end