diff --git a/staging/src/k8s.io/apimachinery/pkg/api/apitesting/naming/naming.go b/staging/src/k8s.io/apimachinery/pkg/api/apitesting/naming/naming.go
index 5b517669533..c235d017e33 100644
--- a/staging/src/k8s.io/apimachinery/pkg/api/apitesting/naming/naming.go
+++ b/staging/src/k8s.io/apimachinery/pkg/api/apitesting/naming/naming.go
@@ -39,7 +39,7 @@ func VerifyGroupNames(scheme *runtime.Scheme, legacyUnsuffixedGroups sets.String
 	errs := []error{}
 	for _, gv := range scheme.PrioritizedVersionsAllGroups() {
 		if !strings.HasSuffix(gv.Group, ".k8s.io") && !legacyUnsuffixedGroups.Has(gv.Group) {
-			errs = append(errs, fmt.Errorf("Group %s does not have the standard kubernetes API group suffix of .k8s.io", gv.Group))
+			errs = append(errs, fmt.Errorf("group %s does not have the standard kubernetes API group suffix of .k8s.io", gv.Group))
 		}
 	}
 	return errors.NewAggregate(errs)
@@ -91,14 +91,14 @@ func ensureNoTags(gvk schema.GroupVersionKind, tp reflect.Type, parents []reflec
 			jsonTag := f.Tag.Get("json")
 			protoTag := f.Tag.Get("protobuf")
 			if len(jsonTag) > 0 || len(protoTag) > 0 {
-				errs = append(errs, fmt.Errorf("Internal types should not have json or protobuf tags. %#v has tag on field %v: %v.\n%s", gvk, f.Name, f.Tag, fmtParentString(parents)))
+				errs = append(errs, fmt.Errorf("internal types should not have json or protobuf tags. %#v has tag on field %v: %v.\n%s", gvk, f.Name, f.Tag, fmtParentString(parents)))
 			}
 
 			errs = append(errs, ensureNoTags(gvk, f.Type, parents, typesAllowedTags)...)
 		}
 
 	default:
-		errs = append(errs, fmt.Errorf("Unexpected type %v in %#v.\n%s", tp.Kind(), gvk, fmtParentString(parents)))
+		errs = append(errs, fmt.Errorf("unexpected type %v in %#v.\n%s", tp.Kind(), gvk, fmtParentString(parents)))
 	}
 	return errs
 }
@@ -140,7 +140,7 @@ func ensureTags(gvk schema.GroupVersionKind, tp reflect.Type, parents []reflect.
 		}
 
 	default:
-		errs = append(errs, fmt.Errorf("Unexpected type %v in %#v.\n%s", tp.Kind(), gvk, fmtParentString(parents)))
+		errs = append(errs, fmt.Errorf("unexpected type %v in %#v.\n%s", tp.Kind(), gvk, fmtParentString(parents)))
 	}
 	return errs
 }
diff --git a/staging/src/k8s.io/apimachinery/pkg/runtime/codec_check.go b/staging/src/k8s.io/apimachinery/pkg/runtime/codec_check.go
index 00022806171..e884007766b 100644
--- a/staging/src/k8s.io/apimachinery/pkg/runtime/codec_check.go
+++ b/staging/src/k8s.io/apimachinery/pkg/runtime/codec_check.go
@@ -30,7 +30,7 @@ import (
 // TODO: verify that the correct external version is chosen on encode...
 func CheckCodec(c Codec, internalType Object, externalTypes ...schema.GroupVersionKind) error {
 	if _, err := Encode(c, internalType); err != nil {
-		return fmt.Errorf("Internal type not encodable: %v", err)
+		return fmt.Errorf("internal type not encodable: %v", err)
 	}
 	for _, et := range externalTypes {
 		typeMeta := TypeMeta{
diff --git a/staging/src/k8s.io/apimachinery/pkg/util/jsonmergepatch/patch.go b/staging/src/k8s.io/apimachinery/pkg/util/jsonmergepatch/patch.go
index e56e177341b..c480ffacbcf 100644
--- a/staging/src/k8s.io/apimachinery/pkg/util/jsonmergepatch/patch.go
+++ b/staging/src/k8s.io/apimachinery/pkg/util/jsonmergepatch/patch.go
@@ -74,7 +74,7 @@ func CreateThreeWayJSONMergePatch(original, modified, current []byte, fns ...mer
 	var patchMap map[string]interface{}
 	err = json.Unmarshal(patch, &patchMap)
 	if err != nil {
-		return nil, fmt.Errorf("Failed to unmarshal patch for precondition check: %s", patch)
+		return nil, fmt.Errorf("failed to unmarshal patch for precondition check: %s", patch)
 	}
 	meetPreconditions, err := meetPreconditions(patchMap, fns...)
 	if err != nil {
diff --git a/staging/src/k8s.io/apimachinery/pkg/util/net/interface.go b/staging/src/k8s.io/apimachinery/pkg/util/net/interface.go
index 82241680648..01d028e727d 100644
--- a/staging/src/k8s.io/apimachinery/pkg/util/net/interface.go
+++ b/staging/src/k8s.io/apimachinery/pkg/util/net/interface.go
@@ -339,7 +339,7 @@ func chooseIPFromHostInterfaces(nw networkInterfacer, addressFamilies AddressFam
 			for _, addr := range addrs {
 				ip, _, err := netutils.ParseCIDRSloppy(addr.String())
 				if err != nil {
-					return nil, fmt.Errorf("Unable to parse CIDR for interface %q: %s", intf.Name, err)
+					return nil, fmt.Errorf("unable to parse CIDR for interface %q: %s", intf.Name, err)
 				}
 				if !memberOf(ip, family) {
 					klog.V(4).Infof("Skipping: no address family match for %q on interface %q.", ip, intf.Name)