diff --git a/RELEASE-NOTES.md b/RELEASE-NOTES.md
index 84245a322..5a11a7c8a 100644
--- a/RELEASE-NOTES.md
+++ b/RELEASE-NOTES.md
@@ -138,6 +138,7 @@ No features have been promoted in this picocli release.
 - [#262] New Feature: new `showDefaultValue` attribute on `@Option` and `@Parameters` gives fine-grained control over which default values to show or hide. Thanks to [ymenager](https://github.com/ymenager) for the request.
 - [#268] New Feature: new `helpCommand` attribute on `@Command`: if the command line arguments contain a subcommand annotated with `helpCommand`, the parser will not validate the required options or positional parameters of the parent command. Thanks to [ymenager](https://github.com/ymenager) for the request.
 - [#277] New Feature: new `hidden` attribute on `@Command` to omit the specified subcommand from the usage help message command list of the parent command. Thanks to [pditommaso](https://github.com/pditommaso).
+- [#279] Enhancement: assign empty String when String option was specified without value. Thanks to [pditommaso](https://github.com/pditommaso) for the request.
 
 ## <a name="3.0.0-alpha-1-deprecated"></a> Deprecations
 
diff --git a/src/test/java/picocli/CommandLineArityTest.java b/src/test/java/picocli/CommandLineArityTest.java
index 594ee42b8..4641f1d01 100644
--- a/src/test/java/picocli/CommandLineArityTest.java
+++ b/src/test/java/picocli/CommandLineArityTest.java
@@ -26,11 +26,7 @@
 import org.junit.Ignore;
 import org.junit.Test;
 
-import picocli.CommandLine.MissingParameterException;
-import picocli.CommandLine.Option;
-import picocli.CommandLine.Parameters;
-import picocli.CommandLine.Range;
-import picocli.CommandLine.UnmatchedArgumentException;
+import picocli.CommandLine.*;
 
 import static org.junit.Assert.*;
 import static picocli.HelpTestUtil.setTraceLevel;
@@ -541,6 +537,22 @@ class App {
                     ": java.lang.NumberFormatException: For input string: \"-boolean\"", ex.getMessage());
         }
     }
+    /** see <a href="https://github.com/remkop/picocli/issues/279">issue #279</a>  */
+    @Test
+    public void testSingleValueFieldWithOptionalParameter_279() {
+        @Command(name="sample")
+        class Sample {
+            @Option(names="--foo", arity="0..1") String foo;
+        }
+        Sample sample1 = CommandLine.populateCommand(new Sample()); // not specified
+        assertNull("optional option is null when option not specified", sample1.foo);
+
+        Sample sample2 = CommandLine.populateCommand(new Sample(), "--foo"); // no arguments
+        assertEquals("optional option is empty string when specified without args", "", sample2.foo);
+
+        Sample sample3 = CommandLine.populateCommand(new Sample(), "--foo", "value"); // no arguments
+        assertEquals("optional option has value when specified", "value", sample3.foo);
+    }
 
     @Test
     public void testIntOptionArity1_nConsumes1Argument() { // ignores varargs
@@ -863,7 +875,7 @@ class Arg {
 
     @Test
     public void test130MixPositionalParamsWithOptions() {
-        @CommandLine.Command(name = "test-command", description = "tests help from a command script")
+        @Command(name = "test-command", description = "tests help from a command script")
         class Arg {
 
             @Parameters(description = "some parameters")
diff --git a/src/test/java/picocli/CommandLineModelTest.java b/src/test/java/picocli/CommandLineModelTest.java
index 2ed798946..699cf1116 100644
--- a/src/test/java/picocli/CommandLineModelTest.java
+++ b/src/test/java/picocli/CommandLineModelTest.java
@@ -23,14 +23,8 @@
 
 import org.junit.Test;
 
-import picocli.CommandLine.CommandSpec;
+import picocli.CommandLine.*;
 import picocli.CommandLine.Help.Ansi;
-import picocli.CommandLine.ITypeConverter;
-import picocli.CommandLine.InitializationException;
-import picocli.CommandLine.OptionSpec;
-import picocli.CommandLine.PositionalParamSpec;
-import picocli.CommandLine.Range;
-import picocli.CommandLine.UnmatchedArgumentException;
 
 import static org.junit.Assert.*;
 import static picocli.HelpTestUtil.setTraceLevel;
@@ -611,4 +605,28 @@ public void testOptionSpecRequiresAtLeastOneName() throws Exception {
     public void testConversion() {
         // TODO convertion with aux types (abstract field types, generic map with and without explicit type attribute etc)
     }
+
+    /** see <a href="https://github.com/remkop/picocli/issues/279">issue #279</a>  */
+    @Test
+    public void testSingleValueFieldWithOptionalParameter_279() {
+        @Command(name="sample")
+        class Sample {
+            @Option(names="--foo", arity="0..1") String foo;
+        }
+        List<CommandLine> parsed1 = new CommandLine(new Sample()).parse();// not specified
+        OptionSpec option1 = parsed1.get(0).getCommandSpec().optionsMap().get("--foo");
+        assertNull("optional option is null when option not specified", option1.getValue());
+        assertTrue("optional option has no raw string value when option not specified", option1.rawStringValues().isEmpty());
+
+        List<CommandLine> parsed2 = new CommandLine(new Sample()).parse("--foo");// specified without value
+        OptionSpec option2 = parsed2.get(0).getCommandSpec().optionsMap().get("--foo");
+        assertEquals("optional option is empty string when specified without args", "", option2.getValue());
+        assertEquals("optional option raw string value when specified without args", "", option2.rawStringValues().get(0));
+
+        List<CommandLine> parsed3 = new CommandLine(new Sample()).parse("--foo", "value");// specified with value
+        OptionSpec option3 = parsed3.get(0).getCommandSpec().optionsMap().get("--foo");
+        assertEquals("optional option is empty string when specified without args", "value", option3.getValue());
+        assertEquals("optional option raw string value when specified without args", "value", option3.rawStringValues().get(0));
+    }
+
 }