diff --git a/python/src/com/jetbrains/python/codeInsight/typing/PyTypingTypeProvider.java b/python/src/com/jetbrains/python/codeInsight/typing/PyTypingTypeProvider.java
index a46d88403f3a..9783b78b6ea1 100644
--- a/python/src/com/jetbrains/python/codeInsight/typing/PyTypingTypeProvider.java
+++ b/python/src/com/jetbrains/python/codeInsight/typing/PyTypingTypeProvider.java
@@ -1268,6 +1268,22 @@ public class PyTypingTypeProvider extends PyTypeProviderBase {
                                 superClass -> superClass != null && PROTOCOL.equals(superClass.getClassQName()));
   }
 
+  public static boolean matchingProtocolDefinitions(@Nullable PyType expected, @Nullable PyType actual, @NotNull TypeEvalContext context) {
+    if (expected instanceof PyClassLikeType && actual instanceof PyClassLikeType) {
+      final PyClassLikeType expectedClassLikeType = (PyClassLikeType)expected;
+      final PyClassLikeType actualClassLikeType = (PyClassLikeType)actual;
+
+      if (expectedClassLikeType.isDefinition() &&
+          actualClassLikeType.isDefinition() &&
+          isProtocol(expectedClassLikeType, context) &&
+          isProtocol(actualClassLikeType, context)) {
+        return true;
+      }
+    }
+
+    return false;
+  }
+
   @NotNull
   private static String getOpenMode(@NotNull PyFunction function, @NotNull PyCallExpression call, @NotNull TypeEvalContext context) {
     final Map<PyExpression, PyCallableParameter> arguments =
diff --git a/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java b/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java
index 88ded186db58..ac98642c9709 100644
--- a/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java
+++ b/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspection.java
@@ -198,7 +198,7 @@ public class PyTypeCheckerInspection extends PyInspection {
         final PyCallableParameter parameter = entry.getValue();
         final PyType expected = parameter.getArgumentType(myTypeEvalContext);
         final PyType actual = myTypeEvalContext.getType(argument);
-        final boolean matched = PyTypeChecker.match(expected, actual, myTypeEvalContext, substitutions);
+        final boolean matched = matchParameterAndArgument(expected, actual, substitutions);
         result.add(new AnalyzeArgumentResult(argument, expected, substituteGenerics(expected, substitutions), actual, matched));
       }
       final PyCallableParameter positionalContainer = getMappedPositionalContainer(mappedParameters);
@@ -220,7 +220,7 @@ public class PyTypeCheckerInspection extends PyInspection {
       // For an expected type with generics we have to match all the actual types against it in order to do proper generic unification
       if (PyTypeChecker.hasGenerics(expected, myTypeEvalContext)) {
         final PyType actual = PyUnionType.union(arguments.stream().map(e -> myTypeEvalContext.getType(e)).collect(Collectors.toList()));
-        final boolean matched = PyTypeChecker.match(expected, actual, myTypeEvalContext, substitutions);
+        final boolean matched = matchParameterAndArgument(expected, actual, substitutions);
         return arguments.stream()
           .map(argument -> new AnalyzeArgumentResult(argument, expected, expectedWithSubstitutions, actual, matched))
           .collect(Collectors.toList());
@@ -229,13 +229,20 @@ public class PyTypeCheckerInspection extends PyInspection {
         return arguments.stream()
           .map(argument -> {
             final PyType actual = myTypeEvalContext.getType(argument);
-            final boolean matched = PyTypeChecker.match(expected, actual, myTypeEvalContext, substitutions);
+            final boolean matched = matchParameterAndArgument(expected, actual, substitutions);
             return new AnalyzeArgumentResult(argument, expected, expectedWithSubstitutions, actual, matched);
           })
           .collect(Collectors.toList());
       }
     }
 
+    private boolean matchParameterAndArgument(@Nullable PyType parameterType,
+                                              @Nullable PyType argumentType,
+                                              @NotNull Map<PyGenericType, PyType> substitutions) {
+      return PyTypeChecker.match(parameterType, argumentType, myTypeEvalContext, substitutions) &&
+             !PyTypingTypeProvider.matchingProtocolDefinitions(parameterType, argumentType, myTypeEvalContext);
+    }
+
     @Nullable
     private PyType substituteGenerics(@Nullable PyType expectedArgumentType, @NotNull Map<PyGenericType, PyType> substitutions) {
       return PyTypeChecker.hasGenerics(expectedArgumentType, myTypeEvalContext)
diff --git a/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspectionProblemRegistrar.java b/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspectionProblemRegistrar.java
index eff591d759ab..c501523a37f3 100644
--- a/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspectionProblemRegistrar.java
+++ b/python/src/com/jetbrains/python/inspections/PyTypeCheckerInspectionProblemRegistrar.java
@@ -22,6 +22,7 @@ import com.intellij.psi.PsiElement;
 import com.intellij.util.ObjectUtils;
 import com.intellij.util.containers.ContainerUtil;
 import com.intellij.xml.util.XmlStringUtil;
+import com.jetbrains.python.codeInsight.typing.PyTypingTypeProvider;
 import com.jetbrains.python.documentation.PythonDocumentationProvider;
 import com.jetbrains.python.psi.*;
 import com.jetbrains.python.psi.types.PyClassLikeType;
@@ -111,6 +112,10 @@ class PyTypeCheckerInspectionProblemRegistrar {
                                                                                         argumentResult.getExpectedTypeAfterSubstitution(),
                                                                                         context);
 
+    if (PyTypingTypeProvider.matchingProtocolDefinitions(expectedType, actualType, context)) {
+      return "Only concrete class can be given where " + expectedTypeRepresentation + " is expected";
+    }
+
     return String.format("Expected type %s, got '%s' instead", expectedTypeRepresentation, actualTypeName);
   }
 
diff --git a/python/testData/inspections/PyTypeCheckerInspection/AgainstTypingProtocolDefinition.py b/python/testData/inspections/PyTypeCheckerInspection/AgainstTypingProtocolDefinition.py
new file mode 100644
index 000000000000..87a47c26ee60
--- /dev/null
+++ b/python/testData/inspections/PyTypeCheckerInspection/AgainstTypingProtocolDefinition.py
@@ -0,0 +1,55 @@
+from typing import Protocol, Type
+
+
+class Proto(Protocol):
+    def proto(self, i: int) -> None:
+        pass
+
+
+class Concrete1:
+    def proto(self, i: int) -> None:
+        pass
+
+
+class Concrete2(Proto):
+    def proto(self, i: int) -> None:
+        pass
+
+
+class Concrete3:
+    def proto(self, i: str) -> None:
+        pass
+
+
+class Concrete4(Proto):
+    def proto(self, i: str) -> None:
+        pass
+
+
+class NewProto(Proto, Protocol):
+    def new_proto(self, s: str) -> None:
+        pass
+
+
+def foo(cls: Type[Proto]) -> None:
+    pass
+
+
+def bar(*classes: Type[Proto]) -> None:
+    pass
+
+
+foo(<warning descr="Only concrete class can be given where 'Type[Proto]' is expected">Proto</warning>)
+foo(Concrete1)
+foo(Concrete2)
+foo(<warning descr="Expected type 'Type[Proto]', got 'Type[Concrete3]' instead">Concrete3</warning>)
+foo(Concrete4)  # matched as inheritor
+foo(<warning descr="Only concrete class can be given where 'Type[Proto]' is expected">NewProto</warning>)
+
+
+bar(<warning descr="Only concrete class can be given where 'Type[Proto]' is expected">Proto</warning>)
+bar(Concrete1)
+bar(Concrete2)
+bar(<warning descr="Expected type 'Type[Proto]', got 'Type[Concrete3]' instead">Concrete3</warning>)
+bar(Concrete4)  # matched as inheritor
+bar(<warning descr="Only concrete class can be given where 'Type[Proto]' is expected">NewProto</warning>)
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
index 7340798045da..9b367326165c 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
@@ -510,4 +510,9 @@ public class PyTypeCheckerInspectionTest extends PyInspectionTestCase {
   public void testTypingProtocolAgainstProtocol() {
     runWithLanguageLevel(LanguageLevel.PYTHON36, this::doTest);
   }
+
+  // PY-26628
+  public void testAgainstTypingProtocolDefinition() {
+    runWithLanguageLevel(LanguageLevel.PYTHON35, this::doTest);
+  }
 }