diff --git a/altsrc/flag.go b/altsrc/flag.go
index daac809..1783e1b 100644
--- a/altsrc/flag.go
+++ b/altsrc/flag.go
@@ -142,13 +142,15 @@ func (f *BoolFlag) ApplyInputSourceValue(cCtx *cli.Context, isc InputSourceConte
 // ApplyInputSourceValue applies a String value to the flagSet if required
 func (f *StringFlag) ApplyInputSourceValue(cCtx *cli.Context, isc InputSourceContext) error {
 	if f.set != nil && !(cCtx.IsSet(f.Name) || isEnvVarSet(f.EnvVars)) && isc.isSet(f.StringFlag.Name) {
-		value, err := isc.String(f.StringFlag.Name)
-		if err != nil {
-			return err
-		}
-		if value != "" {
-			for _, name := range f.Names() {
-				_ = f.set.Set(name, value)
+		for _, name := range f.StringFlag.Names(){
+			if isc.isSet(name) {
+				value, err := isc.String(name)
+				if err != nil {
+					return err
+				}
+				for _, n := range f.Names() {
+					_ = f.set.Set(n, value)
+				}
 			}
 		}
 	}
diff --git a/altsrc/flag_test.go b/altsrc/flag_test.go
index d97c184..47a280a 100644
--- a/altsrc/flag_test.go
+++ b/altsrc/flag_test.go
@@ -220,6 +220,20 @@ func TestBoolApplyInputSourceMethodEnvVarSet(t *testing.T) {
 	refute(t, true, c.Bool("test"))
 }
 
+func TestStringApplyInputSourceMethodSet_Alias(t *testing.T) {
+	tis := testApplyInputSource{
+		Flag:     NewStringFlag(&cli.StringFlag{Name: "test", Aliases: []string{"test_alias"}}),
+		FlagName: "test_alias",
+		MapValue: "hello",
+		ContextValueString: "goodbye",
+	}
+	c := runTest(t, tis)
+	expect(t, "goodbye", c.String("test_alias"))
+
+	c = runRacyTest(t, tis)
+	refute(t, "goodbye", c.String("test_alias"))
+}
+
 func TestStringApplyInputSourceMethodSet(t *testing.T) {
 	tis := testApplyInputSource{
 		Flag:     NewStringFlag(&cli.StringFlag{Name: "test"}),