diff --git a/command/fix/fixer.go b/command/fix/fixer.go
index a1980d432..fca464c5a 100644
--- a/command/fix/fixer.go
+++ b/command/fix/fixer.go
@@ -6,6 +6,10 @@ type Fixer interface {
 	// in some way, and returns the new, transformed structure. The
 	// Fix method is allowed to mutate the input.
 	Fix(input map[string]interface{}) (map[string]interface{}, error)
+
+	// Synopsis returns a string description of what the fixer actually
+	// does.
+	Synopsis() string
 }
 
 // Fixers is the map of all available fixers, by name.
diff --git a/command/fix/fixer_createtime.go b/command/fix/fixer_createtime.go
index b2640619c..81d23bfe0 100644
--- a/command/fix/fixer_createtime.go
+++ b/command/fix/fixer_createtime.go
@@ -49,3 +49,7 @@ func (FixerCreateTime) Fix(input map[string]interface{}) (map[string]interface{}
 	input["builders"] = tpl.Builders
 	return input, nil
 }
+
+func (FixerCreateTime) Synopsis() string {
+	return `Replaces ".CreateTime" in builder configs with "{{timestamp}}"`
+}
diff --git a/command/fix/fixer_iso_md5.go b/command/fix/fixer_iso_md5.go
index 0b14f45e1..3d463e1b0 100644
--- a/command/fix/fixer_iso_md5.go
+++ b/command/fix/fixer_iso_md5.go
@@ -41,3 +41,7 @@ func (FixerISOMD5) Fix(input map[string]interface{}) (map[string]interface{}, er
 	input["builders"] = tpl.Builders
 	return input, nil
 }
+
+func (FixerISOMD5) Synopsis() string {
+	return `Replaces "iso_md5" in builders with "iso_checksum"`
+}
diff --git a/command/fix/fixer_virtualbox_gaattach.go b/command/fix/fixer_virtualbox_gaattach.go
index 6341394c8..0014018ed 100644
--- a/command/fix/fixer_virtualbox_gaattach.go
+++ b/command/fix/fixer_virtualbox_gaattach.go
@@ -57,3 +57,7 @@ func (FixerVirtualBoxGAAttach) Fix(input map[string]interface{}) (map[string]int
 	input["builders"] = tpl.Builders
 	return input, nil
 }
+
+func (FixerVirtualBoxGAAttach) Synopsis() string {
+	return `Updates VirtualBox builders using "guest_additions_attach" to use "guest_additions_mode"`
+}