diff --git a/hcl2template/plugin.go b/hcl2template/plugin.go
index c0f94e3f9..d0cd211fb 100644
--- a/hcl2template/plugin.go
+++ b/hcl2template/plugin.go
@@ -7,12 +7,14 @@ import (
 	"crypto/sha256"
 	"fmt"
 	"log"
+	"os"
 	"runtime"
 	"strings"
 
 	"github.com/hashicorp/hcl/v2"
 	"github.com/hashicorp/packer-plugin-sdk/didyoumean"
 	pluginsdk "github.com/hashicorp/packer-plugin-sdk/plugin"
+	"github.com/hashicorp/packer/packer"
 	plugingetter "github.com/hashicorp/packer/packer/plugin-getter"
 )
 
@@ -132,6 +134,15 @@ func (cfg *PackerConfig) DetectPluginBinaries(releaseOnly bool) hcl.Diagnostics
 		})
 	}
 
+	// If no installed plugin is incompatible with Protobuf, we setup the
+	// environment before invoking any plugin so that they are setup to
+	// use protobuf.
+	if packer.UseProtobuf {
+		os.Setenv("PACKER_RPC_PB", "1")
+	} else {
+		os.Setenv("PACKER_RPC_PB", "0")
+	}
+
 	return diags
 }
 
diff --git a/main.go b/main.go
index 553c173f4..4ee91088e 100644
--- a/main.go
+++ b/main.go
@@ -194,6 +194,11 @@ func wrappedMain() int {
 	// the arguments...
 	args, machineReadable := extractMachineReadable(os.Args[1:])
 
+	// Set potential protobuf usage off if requested
+	if !packer.MayUseProtobuf() {
+		packer.UseProtobuf = false
+	}
+
 	defer packer.CleanupClients()
 
 	var ui packersdk.Ui
diff --git a/packer/core.go b/packer/core.go
index 369ead37f..efca9f305 100644
--- a/packer/core.go
+++ b/packer/core.go
@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"log"
+	"os"
 	"regexp"
 	"sort"
 	"strconv"
@@ -147,6 +148,15 @@ func (c *Core) DetectPluginBinaries(releaseOnly bool) hcl.Diagnostics {
 		})
 	}
 
+	// If no installed plugin is incompatible with Protobuf, we setup the
+	// environment before invoking any plugin so that they are setup to
+	// use protobuf.
+	if UseProtobuf {
+		os.Setenv("PACKER_RPC_PB", "1")
+	} else {
+		os.Setenv("PACKER_RPC_PB", "0")
+	}
+
 	return diags
 }
 
diff --git a/packer/env.go b/packer/env.go
new file mode 100644
index 000000000..0cc28eb21
--- /dev/null
+++ b/packer/env.go
@@ -0,0 +1,25 @@
+package packer
+
+import (
+	"os"
+
+	"github.com/hashicorp/packer-plugin-sdk/rpc"
+)
+
+// MayUseProtobuf is meant to look into the environment to prohibit protobuf
+//
+// If the PACKER_USE_PB environment variable is unset or set to a non-empty
+// string that is neither "0", "no", or "false", Packer will choose dynamically
+// which protocol to use when communicating with plugins.
+//
+// If however it is explicitly set to one of the false values, Packer will not
+// attempt to detect which protocol to use, and instead will forcibly use gob.
+func MayUseProtobuf() bool {
+	usePB := os.Getenv(rpc.PackerUsePBEnvVar)
+	switch usePB {
+	case "0", "no", "false":
+		return false
+	}
+
+	return true
+}
diff --git a/packer/plugin.go b/packer/plugin.go
index 96ff96734..570e4036f 100644
--- a/packer/plugin.go
+++ b/packer/plugin.go
@@ -6,6 +6,7 @@ package packer
 import (
 	"crypto/sha256"
 	"encoding/json"
+	"fmt"
 	"log"
 	"os"
 	"os/exec"
@@ -13,6 +14,7 @@ import (
 	"path/filepath"
 	"regexp"
 	"runtime"
+	"strconv"
 	"strings"
 
 	packersdk "github.com/hashicorp/packer-plugin-sdk/packer"
@@ -42,6 +44,16 @@ const PACKERSPACE = "-PACKERSPACE-"
 
 var extractPluginBasename = regexp.MustCompile("^packer-plugin-([^_]+)")
 
+// UseProtobuf is updated when plugins are discovered.
+//
+// If any plugin is discovered that doesn't support protobuf encoding for
+// their HCL specs, Packer will only use Gob, and avertise as such to the
+// plugins it uses.
+//
+// TODO: check if we can dynamically switch serialisation formats without
+// being too intrusive for plugins.
+var UseProtobuf bool = true
+
 // Discover discovers the latest installed version of each installed plugin.
 //
 // Search the directory of the executable, then the plugins directory, and
@@ -114,6 +126,8 @@ func (c *PluginConfig) Discover(releasesOnly bool) error {
 	return nil
 }
 
+var apiVersionMinorRe = regexp.MustCompile("[0-9]+$")
+
 // DiscoverMultiPlugin takes the description from a multi-component plugin
 // binary and makes the plugins available to use in Packer. Each plugin found in the
 // binary will be addressable using `${pluginName}-${builderName}` for example.
@@ -131,6 +145,23 @@ func (c *PluginConfig) DiscoverMultiPlugin(pluginName, pluginPath string) error
 		return err
 	}
 
+	// If the major version isn't a match with what Packer expects, the
+	// plugin won't be considered for loading, so we can safely ignore that
+	// check here, and only check that the version is at least 5.1 for
+	// protobuf support.
+	// So by only looking at the minor version number, we'll be good here,
+	// at least until we officially remove gob support in v6.0, in which
+	// case, this check will be removed.
+	minVersion := apiVersionMinorRe.FindString(desc.APIVersion)
+	if minVersion == "" {
+		return fmt.Errorf("plugin API minor number could not be extracted, this is a Packer bug, please open an issue on the project tracker.")
+	}
+	minNb, _ := strconv.Atoi(minVersion)
+	if minNb == 0 {
+		log.Printf("[DEBUG] - plugin %q uses an older SDK, won't attempt to use protobuf for serialisation", pluginName)
+		UseProtobuf = false
+	}
+
 	pluginPrefix := pluginName + "-"
 
 	for _, builderName := range desc.Builders {