diff --git a/README.md b/README.md
index a2ff0e3..3a4d962 100644
--- a/README.md
+++ b/README.md
@@ -43,9 +43,9 @@ Environment: `MCP_REGION`.
 * `ddcloud-networkdomain` - The name of the target CloudControl network domain.
 * `ddcloud-datacenter` - The name of the CloudControl datacenter (e.g. NA1, AU9) in which the network domain is located.
 * `ddcloud-vlan` - The name of the target CloudControl VLAN.
-* `ddcloud-memorygb` - The amount of RAM in GB for the target machine. (Default 4GB)
-* `ddcloud-cpucount` - The amount of CPUs for the target machine. (Default: 2)
-* `ddcloud-corespersocket` - The amount of cores per socket for the target machine. (Default: 2)
+* `ddcloud-memorygb` - The amount of RAM in GB for the target machine. (Default: taken from image)
+* `ddcloud-cpucount` - The amount of CPUs for the target machine. (Default: taken from image)
+* `ddcloud-corespersocket` - The amount of cores per socket for the target machine. (Default: taken from image)
 * `ddcloud-image-name` - The name of the image used to create the target machine.
 Additionally, the OS must be a Linux distribution supported by docker-machine (Ubuntu 12.04 and above are supported, but RedHat 6 and 7 are not supported due to iptables configuration issues).
 * `ddcloud-ssh-user` - The SSH username to use.
diff --git a/client.go b/client.go
index f72cc85..c2aa9ec 100644
--- a/client.go
+++ b/client.go
@@ -336,9 +336,15 @@ func (driver *Driver) buildDeploymentConfiguration() (deploymentConfiguration co
 	image.ApplyTo(&deploymentConfiguration)
 
 	// Customise memory and / or CPU (if required).
-	deploymentConfiguration.MemoryGB = driver.MemoryGB
-	deploymentConfiguration.CPU.Count = driver.CPUCount
-	deploymentConfiguration.CPU.CoresPerSocket = driver.CoresPerSocket
+	if driver.MemoryGB != -1 {
+		deploymentConfiguration.MemoryGB = driver.MemoryGB
+	}
+	if driver.CPUCount != -1 {
+		deploymentConfiguration.CPU.Count = driver.CPUCount
+	}
+	if driver.CoresPerSocket != -1 {
+		deploymentConfiguration.CPU.CoresPerSocket = driver.CoresPerSocket
+	}
 
 	return
 }
diff --git a/driver.go b/driver.go
index 8088d40..8f492ef 100644
--- a/driver.go
+++ b/driver.go
@@ -210,18 +210,18 @@ func (driver *Driver) GetCreateFlags() []mcnflag.Flag {
 		},
 		mcnflag.IntFlag{
 			Name:  "ddcloud-memorygb",
-			Usage: "The amount of RAM in GB for the target machine. Default: 4",
-			Value: 4,
+			Usage: "The amount of RAM in GB for the target machine. Default: -1 (Image default)",
+			Value: -1,
 		},
 		mcnflag.IntFlag{
 			Name:  "ddcloud-cpucount",
-			Usage: "The amount of CPUs for the target machine. Default: 2",
-			Value: 2,
+			Usage: "The amount of CPUs for the target machine. Default: -1 (Image default)",
+			Value: -1,
 		},
 		mcnflag.IntFlag{
 			Name:  "ddcloud-corespersocket",
-			Usage: "The amount of cores per socket for the target machine. Default: 2",
-			Value: 2,
+			Usage: "The amount of cores per socket for the target machine. Default: -1 (Image default)",
+			Value: -1,
 		},
 	}
 }