diff --git a/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs b/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
index ea332084ca..00e2459f09 100644
--- a/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
+++ b/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
@@ -488,9 +488,10 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             }
             else
             {
-                // The set has no suffix, so we're just looking for an exact match (which means that if 'this'
-                // has a suffix, it won't match).
-                return set.SubType.Equals(SubType, StringComparison.OrdinalIgnoreCase);
+                // If this subtype or suffix matches the subtype of the set,
+                // it is considered a subtype.
+                // Ex: application/json > application/val+json
+                return MatchesEitherSubtypeOrSuffix(set);
             }
         }
 
@@ -507,6 +508,12 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             return set.SubTypeSuffix.Equals(SubTypeSuffix, StringComparison.OrdinalIgnoreCase);
         }
 
+        private bool MatchesEitherSubtypeOrSuffix(MediaType set)
+        {
+            return set.SubType.Equals(SubType, StringComparison.OrdinalIgnoreCase) ||
+                set.SubType.Equals(SubTypeSuffix, StringComparison.OrdinalIgnoreCase);
+        }
+
         private bool ContainsAllParameters(MediaTypeParameterParser setParameters)
         {
             var parameterFound = true;
diff --git a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/InputFormatterTest.cs b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/InputFormatterTest.cs
index 2ad5752053..d5b631d9b6 100644
--- a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/InputFormatterTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/InputFormatterTest.cs
@@ -265,6 +265,9 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
 
         [Theory]
         [InlineData("application/xml")]
+        [InlineData("application/mathml-content+xml")]
+        [InlineData("application/mathml-presentation+xml")]
+        [InlineData("application/mathml+xml; test=value")]
         public void XMLFormatter_CanRead_ReturnsTrueForSupportedMediaTypes(string requestContentType)
         {
             // Arrange
@@ -289,9 +292,6 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         }
 
         [Theory]
-        [InlineData("application/mathml-content+xml")]
-        [InlineData("application/mathml-presentation+xml")]
-        [InlineData("application/mathml+xml; undefined=ignored")]
         [InlineData("application/octet-stream; padding=3")]
         [InlineData("application/xml-dtd; undefined=ignored")]
         [InlineData("multipart/mixed; boundary=gc0p4Jq0M2Yt08j34c0p")]
diff --git a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
index 28591cf017..9ab131f8ec 100644
--- a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
@@ -214,6 +214,8 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         [InlineData("application/entity+json", "application/entity+json")]
         [InlineData("application/*+json", "application/entity+json")]
         [InlineData("application/*", "application/entity+json")]
+        [InlineData("application/json", "application/vnd.restful+json")]
+        [InlineData("application/json", "application/problem+json")]
         public void IsSubsetOf_ReturnsTrueWhenExpected(string set, string subset)
         {
             // Arrange
@@ -242,6 +244,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         [InlineData("application/*+*", "application/json")]
         [InlineData("application/entity+*", "application/entity+json")] // We don't allow suffixes to be wildcards
         [InlineData("application/*+*", "application/entity+json")] // We don't allow suffixes to be wildcards
+        [InlineData("application/entity+json", "application/entity")]
         public void IsSubsetOf_ReturnsFalseWhenExpected(string set, string subset)
         {
             // Arrange
diff --git a/test/Microsoft.AspNetCore.Mvc.Formatters.Json.Test/JsonInputFormatterTest.cs b/test/Microsoft.AspNetCore.Mvc.Formatters.Json.Test/JsonInputFormatterTest.cs
index d17e4748fa..30868308ad 100644
--- a/test/Microsoft.AspNetCore.Mvc.Formatters.Json.Test/JsonInputFormatterTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.Formatters.Json.Test/JsonInputFormatterTest.cs
@@ -254,7 +254,7 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
         [InlineData("application/some.entity+json;v=2", true)]
         [InlineData("application/some.entity+xml", false)]
         [InlineData("application/some.entity+*", false)]
-        [InlineData("text/some.entity+json", false)]
+        [InlineData("text/some.entity+json", true)]
         [InlineData("", false)]
         [InlineData(null, false)]
         [InlineData("invalid", false)]