diff --git a/python/src/com/jetbrains/python/psi/impl/PyBinaryExpressionImpl.java b/python/src/com/jetbrains/python/psi/impl/PyBinaryExpressionImpl.java
index a400c5a3d5e3..30b0b885a57c 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyBinaryExpressionImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyBinaryExpressionImpl.java
@@ -159,15 +159,9 @@ public class PyBinaryExpressionImpl extends PyElementImpl implements PyBinaryExp
 
         boolean matched = true;
         for (Map.Entry<PyExpression, PyCallableParameter> entry : result.getMappedParameters().entrySet()) {
-          final PyExpression argument = entry.getKey();
-          final PyCallableParameter parameter = entry.getValue();
-          if (parameter.isPositionalContainer() || parameter.isKeywordContainer()) {
-            continue;
-          }
-          final Map<PyGenericType, PyType> substitutions = new HashMap<>();
-          final PyType parameterType = parameter.getType(context);
-          final PyType argumentType = context.getType(argument);
-          if (!PyTypeChecker.match(parameterType, argumentType, context, substitutions)) {
+          final PyType parameterType = entry.getValue().getArgumentType(context);
+          final PyType argumentType = context.getType(entry.getKey());
+          if (!PyTypeChecker.match(parameterType, argumentType, context, new HashMap<>())) {
             matched = false;
           }
         }
@@ -179,11 +173,11 @@ public class PyBinaryExpressionImpl extends PyElementImpl implements PyBinaryExp
           }
         }
       }
-      if (!matchedTypes.isEmpty()) {
-        return PyUnionType.union(matchedTypes);
-      }
-      if (!types.isEmpty()) {
-        return PyUnionType.union(types);
+      final boolean bothOperandsAreKnown = operandIsKnown(getLeftExpression(), context) && operandIsKnown(getRightExpression(), context);
+      final List<PyType> resultTypes = !matchedTypes.isEmpty() ? matchedTypes : types;
+      if (!resultTypes.isEmpty()) {
+        final PyType result = PyUnionType.union(resultTypes);
+        return bothOperandsAreKnown ? result : PyUnionType.createWeakType(result);
       }
     }
     if (PyNames.COMPARISON_OPERATORS.contains(getReferencedName())) {
@@ -223,6 +217,15 @@ public class PyBinaryExpressionImpl extends PyElementImpl implements PyBinaryExp
     return op != null ? op.getNode() : null;
   }
 
+  private static boolean operandIsKnown(@Nullable PyExpression operand, @NotNull TypeEvalContext context) {
+    if (operand == null) return false;
+
+    final PyType operandType = context.getType(operand);
+    if (operandType instanceof PyStructuralType || PyTypeChecker.isUnknown(operandType, context)) return false;
+
+    return true;
+  }
+
   private static boolean isTrueDivEnabled(@NotNull PyElement anchor) {
     final PsiFile file = anchor.getContainingFile();
     if (file instanceof PyFile) {
diff --git a/python/testData/inspections/PyTypeCheckerInspection/BinaryExpressionWithUnknownOperand.py b/python/testData/inspections/PyTypeCheckerInspection/BinaryExpressionWithUnknownOperand.py
new file mode 100644
index 000000000000..c690b938735b
--- /dev/null
+++ b/python/testData/inspections/PyTypeCheckerInspection/BinaryExpressionWithUnknownOperand.py
@@ -0,0 +1,17 @@
+from typing import Any
+
+
+def f(x: Any) -> str:
+    return x * 2
+
+
+def f(x: Any) -> str:
+    return 2 * x
+
+
+def f(x) -> str:
+    return x * 2
+
+
+def f(x) -> str:
+    return 2 * x
\ No newline at end of file
diff --git a/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py b/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
index 32540fec5a80..fe2d2c35cff8 100644
--- a/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
+++ b/python/testData/inspections/PyTypeCheckerInspection/MapReturnElementType.py
@@ -1,5 +1,5 @@
 def test():
     xs = map(lambda x: x + 1, [1, 2, 3])
-    print('foo' + <warning descr="Expected type 'TypeVar('AnyStr', str, unicode)', got 'int' instead">xs[0]</warning>)
+    print('foo' + xs[0])
     ys = map(tuple, iter([1, 2, 3]))
     print(1 + <warning descr="Expected type 'int', got 'tuple' instead">ys[0]</warning>, 'bar' + <warning descr="Expected type 'TypeVar('AnyStr', str, unicode)', got 'tuple' instead">ys[1]</warning>)
diff --git a/python/testSrc/com/jetbrains/python/PyTypeTest.java b/python/testSrc/com/jetbrains/python/PyTypeTest.java
index 74734d6cbf95..ba611eb66edd 100644
--- a/python/testSrc/com/jetbrains/python/PyTypeTest.java
+++ b/python/testSrc/com/jetbrains/python/PyTypeTest.java
@@ -2237,6 +2237,32 @@ public class PyTypeTest extends PyTestCase {
     );
   }
 
+  // PY-9662
+  public void testBinaryExpressionWithUnknownOperand() {
+    runWithLanguageLevel(
+      LanguageLevel.PYTHON35,
+      () -> {
+        doTest("Union[int, Any]",
+               "from typing import Any\n" +
+               "x: Any\n" +
+               "expr = x * 2");
+
+        doTest("Union[int, Any]",
+               "from typing import Any\n" +
+               "x: Any\n" +
+               "expr = 2 * x");
+
+        doTest("Union[int, Any]",
+               "def f(x):\n" +
+               "    expr = x * 2");
+
+        doTest("Union[int, Any]",
+               "def f(x):\n" +
+               "    expr = 2 * x");
+      }
+    );
+  }
+
   private static List<TypeEvalContext> getTypeEvalContexts(@NotNull PyExpression element) {
     return ImmutableList.of(TypeEvalContext.codeAnalysis(element.getProject(), element.getContainingFile()).withTracing(),
                             TypeEvalContext.userInitiated(element.getProject(), element.getContainingFile()).withTracing());
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
index 44f6f553c665..10d1c830cb98 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyTypeCheckerInspectionTest.java
@@ -442,6 +442,11 @@ public class PyTypeCheckerInspectionTest extends PyTestCase {
     doTest();
   }
 
+  // PY-9662
+  public void testBinaryExpressionWithUnknownOperand() {
+    runWithLanguageLevel(LanguageLevel.PYTHON35, this::doTest);
+  }
+
   // PY-16066
   public void testBasestringMatchesType() {
     doTest();