diff --git a/builder/docker/comm.go b/builder/docker/comm.go
index c064c0550..8af3d57ca 100644
--- a/builder/docker/comm.go
+++ b/builder/docker/comm.go
@@ -36,6 +36,7 @@ func sshConfig(comm *communicator.Config) func(state multistep.StateBag) (*gossh
 				Auth: []gossh.AuthMethod{
 					gossh.PublicKeys(signer),
 				},
+				HostKeyCallback: gossh.InsecureIgnoreHostKey(),
 			}, nil
 		} else {
 			// password based auth
@@ -46,6 +47,7 @@ func sshConfig(comm *communicator.Config) func(state multistep.StateBag) (*gossh
 					gossh.KeyboardInteractive(
 						ssh.PasswordKeyboardInteractive(comm.SSHPassword)),
 				},
+				HostKeyCallback: gossh.InsecureIgnoreHostKey(),
 			}, nil
 		}
 	}
diff --git a/builder/null/ssh.go b/builder/null/ssh.go
index 1cbf4ceac..b8dea896e 100644
--- a/builder/null/ssh.go
+++ b/builder/null/ssh.go
@@ -39,6 +39,7 @@ func SSHConfig(useAgent bool, username string, password string, privateKeyFile s
 				Auth: []gossh.AuthMethod{
 					gossh.PublicKeysCallback(agent.NewClient(sshAgent).Signers),
 				},
+				HostKeyCallback: gossh.InsecureIgnoreHostKey(),
 			}, nil
 		}
 
@@ -61,6 +62,7 @@ func SSHConfig(useAgent bool, username string, password string, privateKeyFile s
 				Auth: []gossh.AuthMethod{
 					gossh.PublicKeys(signer),
 				},
+				HostKeyCallback: gossh.InsecureIgnoreHostKey(),
 			}, nil
 		} else {
 			// password based auth
diff --git a/builder/vmware/iso/driver_esx5.go b/builder/vmware/iso/driver_esx5.go
index bcd71cbd4..9f557b540 100644
--- a/builder/vmware/iso/driver_esx5.go
+++ b/builder/vmware/iso/driver_esx5.go
@@ -395,8 +395,9 @@ func (d *ESX5Driver) connect() error {
 	sshConfig := &ssh.Config{
 		Connection: ssh.ConnectFunc("tcp", address),
 		SSHConfig: &gossh.ClientConfig{
-			User: d.Username,
-			Auth: auth,
+			User:            d.Username,
+			Auth:            auth,
+			HostKeyCallback: gossh.InsecureIgnoreHostKey(),
 		},
 	}