diff --git a/lib/fog/aws/ec2.rb b/lib/fog/aws/ec2.rb
index 678a905c5..c78b7f594 100644
--- a/lib/fog/aws/ec2.rb
+++ b/lib/fog/aws/ec2.rb
@@ -152,6 +152,7 @@
           @aws_access_key_id      = options[:aws_access_key_id]
           @aws_secret_access_key  = options[:aws_secret_access_key]
           @hmac = Fog::HMAC.new('sha256', @aws_secret_access_key)
+          options[:region] ||= 'us-east-1'
           @host = options[:host] || case options[:region]
             when 'ap-southeast-1'
               'ec2.ap-southeast-1.amazonaws.com'
@@ -162,7 +163,7 @@
             when 'us-west-1'
               'ec2.us-west-1.amazonaws.com'
             else
-              'ec2.amazonaws.com'
+              raise ArgumentError, "Unknown region: #{options[:region].inspect}"
             end
           @port   = options[:port]      || 443
           @scheme = options[:scheme]    || 'https'
diff --git a/lib/fog/aws/elb.rb b/lib/fog/aws/elb.rb
index f9f67b29c..2dc0d497b 100644
--- a/lib/fog/aws/elb.rb
+++ b/lib/fog/aws/elb.rb
@@ -49,6 +49,7 @@ module Fog
           @aws_access_key_id      = options[:aws_access_key_id]
           @aws_secret_access_key  = options[:aws_secret_access_key]
           @hmac = Fog::HMAC.new('sha256', @aws_secret_access_key)
+          options[:region] ||= 'us-east-1'
           @host = options[:host] || case options[:region]
           when 'ap-southeast-1'
             'elasticloadbalancing.ap-southeast-1.amazonaws.com'
@@ -59,7 +60,7 @@ module Fog
           when 'us-west-1'
             'elasticloadbalancing.us-west-1.amazonaws.com'
           else
-            'elasticloadbalancing.amazonaws.com'
+            raise ArgumentError, "Unknown region: #{options[:region].inspect}"
           end
           @port       = options[:port]      || 443
           @scheme     = options[:scheme]    || 'https'
diff --git a/lib/fog/aws/s3.rb b/lib/fog/aws/s3.rb
index 4716405da..c3bc0b6fc 100644
--- a/lib/fog/aws/s3.rb
+++ b/lib/fog/aws/s3.rb
@@ -125,13 +125,16 @@ module Fog
           @aws_access_key_id = options[:aws_access_key_id]
           @aws_secret_access_key = options[:aws_secret_access_key]
           @hmac = Fog::HMAC.new('sha1', @aws_secret_access_key)
+          options[:region] ||= 'us-east-1'
           @host = options[:host] || case options[:region]
+            when 'us-east-1'
+              's3.amazonaws.com'
             when 'ap-southeast-1'
               's3-ap-southeast-1.amazonaws.com'
             when 'us-west-1'
               's3-us-west-1.amazonaws.com'
             else
-              's3.amazonaws.com'
+              raise ArgumentError, "Unknown region: #{options[:region].inspect}"
             end
           @port   = options[:port]      || 443
           @scheme = options[:scheme]    || 'https'