diff --git a/src/WireMock.Net/Matchers/Request/RequestMessageParamMatcher.cs b/src/WireMock.Net/Matchers/Request/RequestMessageParamMatcher.cs
index 1564ef32d..604f0880d 100644
--- a/src/WireMock.Net/Matchers/Request/RequestMessageParamMatcher.cs
+++ b/src/WireMock.Net/Matchers/Request/RequestMessageParamMatcher.cs
@@ -27,6 +27,14 @@ public class RequestMessageParamMatcher : IRequestMatcher
         /// </summary>
         public IEnumerable<string> Values { get; }
 
+        /// <summary>
+        /// Initializes a new instance of the <see cref="RequestMessageParamMatcher"/> class.
+        /// </summary>
+        /// <param name="key">The key.</param>
+        public RequestMessageParamMatcher([NotNull] string key) : this(key, null)
+        {
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="RequestMessageParamMatcher"/> class.
         /// </summary>
@@ -66,13 +74,19 @@ private double IsMatch(RequestMessage requestMessage)
             }
 
             var values = requestMessage.GetParameter(Key);
-            if (values == null && !Values.Any())
+            if (values == null)
+            {
+                // Key is not present, just return Mismatch
+                return MatchScores.Mismatch;
+            }
+
+            if (values.Count == 0 && (Values == null || !Values.Any()))
             {
-                // Key is present, but no values, just return match
+                // Key is present, but no values or null, just return Perfect
                 return MatchScores.Perfect;
             }
 
-            var matches = Values.Select(v => values != null && values.Contains(v));
+            var matches = Values.Select(v => values.Contains(v));
             return MatchScores.ToScore(matches);
         }
     }
diff --git a/src/WireMock.Net/RequestBuilders/IParamsRequestBuilder.cs b/src/WireMock.Net/RequestBuilders/IParamsRequestBuilder.cs
index 590eefa80..3b1799aa3 100644
--- a/src/WireMock.Net/RequestBuilders/IParamsRequestBuilder.cs
+++ b/src/WireMock.Net/RequestBuilders/IParamsRequestBuilder.cs
@@ -6,12 +6,19 @@
 namespace WireMock.RequestBuilders
 {
     /// <summary>
-    /// The ParametersRequestBuilder interface.
+    /// The ParamsRequestBuilder interface.
     /// </summary>
     public interface IParamsRequestBuilder
     {
         /// <summary>
-        /// The with parameters.
+        /// WithParam (key only)
+        /// </summary>
+        /// <param name="key">The key.</param>
+        /// <returns>The <see cref="IRequestBuilder"/>.</returns>
+        IRequestBuilder WithParam([NotNull] string key);
+
+        /// <summary>
+        /// WithParam (values)
         /// </summary>
         /// <param name="key">The key.</param>
         /// <param name="values">The values.</param>
@@ -19,7 +26,7 @@ public interface IParamsRequestBuilder
         IRequestBuilder WithParam([NotNull] string key, [CanBeNull] params string[] values);
 
         /// <summary>
-        /// The with parameters.
+        /// WithParam (funcs)
         /// </summary>
         /// <param name="funcs">The funcs.</param>
         /// <returns>The <see cref="IRequestBuilder"/>.</returns>
diff --git a/src/WireMock.Net/RequestBuilders/Request.cs b/src/WireMock.Net/RequestBuilders/Request.cs
index 8d527935e..f26e7ce7e 100644
--- a/src/WireMock.Net/RequestBuilders/Request.cs
+++ b/src/WireMock.Net/RequestBuilders/Request.cs
@@ -291,6 +291,15 @@ public IRequestBuilder WithBody(Func<object, bool> func)
             return this;
         }
 
+        /// <inheritdoc cref="IParamsRequestBuilder.WithParam(string)"/>
+        public IRequestBuilder WithParam(string key)
+        {
+            Check.NotNull(key, nameof(key));
+
+            _requestMatchers.Add(new RequestMessageParamMatcher(key));
+            return this;
+        }
+
         /// <inheritdoc cref="IParamsRequestBuilder.WithParam(string, string[])"/>
         public IRequestBuilder WithParam(string key, params string[] values)
         {
diff --git a/src/WireMock.Net/RequestMessage.cs b/src/WireMock.Net/RequestMessage.cs
index 8540c5330..990e03ba9 100644
--- a/src/WireMock.Net/RequestMessage.cs
+++ b/src/WireMock.Net/RequestMessage.cs
@@ -206,7 +206,7 @@ private static IDictionary<string, WireMockList<string>> ParseQuery(string query
         /// </summary>
         /// <param name="key">The key.</param>
         /// <returns>The query parameter.</returns>
-        public List<string> GetParameter(string key)
+        public WireMockList<string> GetParameter(string key)
         {
             if (Query == null)
             {
diff --git a/test/WireMock.Net.Tests/RequestMatchers/RequestMessageParamMatcherTests.cs b/test/WireMock.Net.Tests/RequestMatchers/RequestMessageParamMatcherTests.cs
index c4879ea8a..87560bafa 100644
--- a/test/WireMock.Net.Tests/RequestMatchers/RequestMessageParamMatcherTests.cs
+++ b/test/WireMock.Net.Tests/RequestMatchers/RequestMessageParamMatcherTests.cs
@@ -51,5 +51,35 @@ public void RequestMessageParamMatcher_GetMatchingScore_OnlyKeyPresent()
             // Assert
             Check.That(score).IsEqualTo(0.0d);
         }
+
+        [Fact]
+        public void RequestMessageParamMatcher_GetMatchingScore_OnlyKeyPresent_WithNull()
+        {
+            // Assign
+            var requestMessage = new RequestMessage(new Uri("http://localhost?key"), "GET", "127.0.0.1");
+            var matcher = new RequestMessageParamMatcher("key");
+
+            // Act
+            var result = new RequestMatchResult();
+            double score = matcher.GetMatchingScore(requestMessage, result);
+
+            // Assert
+            Check.That(score).IsEqualTo(1.0d);
+        }
+
+        [Fact]
+        public void RequestMessageParamMatcher_GetMatchingScore_OnlyKeyPresent_WithEmptyArray()
+        {
+            // Assign
+            var requestMessage = new RequestMessage(new Uri("http://localhost?key"), "GET", "127.0.0.1");
+            var matcher = new RequestMessageParamMatcher("key", new string[] { });
+
+            // Act
+            var result = new RequestMatchResult();
+            double score = matcher.GetMatchingScore(requestMessage, result);
+
+            // Assert
+            Check.That(score).IsEqualTo(1.0d);
+        }
     }
 }
\ No newline at end of file