diff --git a/shard.yml b/shard.yml
index a74e92b..557abd2 100644
--- a/shard.yml
+++ b/shard.yml
@@ -4,6 +4,6 @@ version: 0.4.4
 authors:
   - Brian J. Cardiff <bcardiff@manas.tech>
 
-crystal: 0.22.0
+crystal: 0.24.0
 
 license: MIT
diff --git a/spec/database_spec.cr b/spec/database_spec.cr
index 51a53a3..e3aeb79 100644
--- a/spec/database_spec.cr
+++ b/spec/database_spec.cr
@@ -153,7 +153,7 @@ describe DB::Database do
     connection = uninitialized DB::Connection
     with_dummy "dummy://localhost:1027?initial_pool_size=1" do |db|
       connection = DummyDriver::DummyConnection.connections.first
-      expect_raises do
+      expect_raises DB::Error do
         db.prepared.exec("syntax error")
       end
       db.pool.is_available?(connection).should be_true
@@ -164,7 +164,7 @@ describe DB::Database do
     connection = uninitialized DB::Connection
     with_dummy "dummy://localhost:1027?initial_pool_size=1" do |db|
       connection = DummyDriver::DummyConnection.connections.first
-      expect_raises do
+      expect_raises DB::Error do
         db.unprepared.exec("syntax error")
       end
       db.pool.is_available?(connection).should be_true
diff --git a/spec/dummy_driver.cr b/spec/dummy_driver.cr
index b0dcf42..0ef4b80 100644
--- a/spec/dummy_driver.cr
+++ b/spec/dummy_driver.cr
@@ -99,7 +99,7 @@ class DummyDriver < DB::Driver
     def initialize(connection, @query : String, @prepared : Bool)
       @params = Hash(Int32 | String, DB::Any).new
       super(connection)
-      raise query if query == "syntax error"
+      raise DB::Error.new(query) if query == "syntax error"
     end
 
     protected def perform_query(args : Enumerable)
@@ -111,7 +111,7 @@ class DummyDriver < DB::Driver
     protected def perform_exec(args : Enumerable)
       @connection.as(DummyConnection).check
       set_params args
-      raise "forced exception due to query" if @query == "raise"
+      raise DB::Error.new("forced exception due to query") if @query == "raise"
       DB::ExecResult.new 0i64, 0_i64
     end
 
diff --git a/spec/dummy_driver_spec.cr b/spec/dummy_driver_spec.cr
index a853786..c4da05d 100644
--- a/spec/dummy_driver_spec.cr
+++ b/spec/dummy_driver_spec.cr
@@ -278,7 +278,7 @@ describe DummyDriver do
 
     it "should raise executing raise query" do
       with_dummy do |db|
-        expect_raises do
+        expect_raises DB::Error do
           db.exec "raise"
         end
       end
diff --git a/spec/mapping_spec.cr b/spec/mapping_spec.cr
index 4cb6225..dc8f7e6 100644
--- a/spec/mapping_spec.cr
+++ b/spec/mapping_spec.cr
@@ -87,15 +87,21 @@ describe "DB.mapping" do
   end
 
   it "should fail to initialize a simple mapping if types do not match" do
-    expect_raises { from_dummy("b,a", SimpleMapping) }
+    expect_raises ArgumentError do
+      from_dummy("b,a", SimpleMapping)
+    end
   end
 
   it "should fail to initialize a simple mapping if there is a missing column" do
-    expect_raises { from_dummy("1", SimpleMapping) }
+    expect_raises DB::MappingException do
+      from_dummy("1", SimpleMapping)
+    end
   end
 
   it "should fail to initialize a simple mapping if there is an unexpected column" do
-    expect_raises { from_dummy("1,a,b", SimpleMapping) }
+    expect_raises DB::MappingException do
+      from_dummy("1,a,b", SimpleMapping)
+    end
   end
 
   it "should initialize a non-strict mapping if there is an unexpected column" do
diff --git a/spec/statement_spec.cr b/spec/statement_spec.cr
index 70c3385..fcdd05a 100644
--- a/spec/statement_spec.cr
+++ b/spec/statement_spec.cr
@@ -147,7 +147,7 @@ describe DB::Statement do
 
   it "connection should be released if error occurs during exec" do
     with_dummy do |db|
-      expect_raises do
+      expect_raises DB::Error do
         db.exec "raise"
       end
       DummyDriver::DummyConnection.connections.size.should eq(1)