diff --git a/scheduler/feasible.go b/scheduler/feasible.go
index 289fbe03c23..c345cb94dfb 100644
--- a/scheduler/feasible.go
+++ b/scheduler/feasible.go
@@ -606,7 +606,7 @@ func checkLexicalOrder(op string, lVal, rVal interface{}) bool {
 
 // checkVersionMatch is used to compare a version on the
 // left hand side with a set of constraints on the right hand side
-func checkVersionMatch(ctx Context, parse VerConstraintParser, lVal, rVal interface{}) bool {
+func checkVersionMatch(ctx Context, parse verConstraintParser, lVal, rVal interface{}) bool {
 	// Parse the version
 	var versionStr string
 	switch v := lVal.(type) {
@@ -642,7 +642,7 @@ func checkVersionMatch(ctx Context, parse VerConstraintParser, lVal, rVal interf
 
 // checkAttributeVersionMatch is used to compare a version on the
 // left hand side with a set of constraints on the right hand side
-func checkAttributeVersionMatch(ctx Context, parse VerConstraintParser, lVal, rVal *psstructs.Attribute) bool {
+func checkAttributeVersionMatch(ctx Context, parse verConstraintParser, lVal, rVal *psstructs.Attribute) bool {
 	// Parse the version
 	var versionStr string
 	if s, ok := lVal.GetString(); ok {
@@ -1166,14 +1166,18 @@ func checkAttributeConstraint(ctx Context, operand string, lVal, rVal *psstructs
 
 }
 
+// VerConstraints is the interface implemented by both go-verson constraints
+// and semver constraints.
 type VerConstraints interface {
 	Check(v *version.Version) bool
 	String() string
 }
 
-type VerConstraintParser func(verConstraint string) VerConstraints
+// verConstraintParser returns a version constraints implementation (go-version
+// or semver).
+type verConstraintParser func(verConstraint string) VerConstraints
 
-func newVersionConstraintParser(ctx Context) VerConstraintParser {
+func newVersionConstraintParser(ctx Context) verConstraintParser {
 	cache := ctx.VersionConstraintCache()
 
 	return func(cstr string) VerConstraints {
@@ -1191,7 +1195,7 @@ func newVersionConstraintParser(ctx Context) VerConstraintParser {
 	}
 }
 
-func newSemverConstraintParser(ctx Context) VerConstraintParser {
+func newSemverConstraintParser(ctx Context) verConstraintParser {
 	cache := ctx.SemverConstraintCache()
 
 	return func(cstr string) VerConstraints {