diff --git a/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java b/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
index 7c89a1c4770c..76e96692194c 100644
--- a/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
+++ b/python/src/com/jetbrains/python/psi/impl/PyNamedParameterImpl.java
@@ -349,11 +349,29 @@ public class PyNamedParameterImpl extends PyBaseElementImpl<PyNamedParameterStub
   }
 
   @Nullable
-  private static PyNamedParameter getParameterByCallArgument(@NotNull PsiElement element, @NotNull TypeEvalContext context) {
-    final PyCallExpression call = PsiTreeUtil.getParentOfType(element, PyCallExpression.class);
-    if (call != null) {
-      final PyArgumentList argumentList = call.getArgumentList();
-      if (argumentList != null) {
+  private PyNamedParameter getParameterByCallArgument(@NotNull PsiElement element, @NotNull TypeEvalContext context) {
+    final PyArgumentList argumentList = PsiTreeUtil.getParentOfType(element, PyArgumentList.class);
+    if (argumentList != null) {
+      boolean elementIsArgument = false;
+      for (PyExpression argument : argumentList.getArgumentExpressions()) {
+        if (PyPsiUtils.flattenParens(argument) == element) {
+          elementIsArgument = true;
+          break;
+        }
+      }
+      final PyCallExpression callExpression = argumentList.getCallExpression();
+      if (elementIsArgument && callExpression != null) {
+        final PyExpression callee = callExpression.getCallee();
+        if (callee instanceof PyReferenceExpression) {
+          final PyReferenceExpression calleeReferenceExpr = (PyReferenceExpression)callee;
+          final PyExpression firstQualifier = PyPsiUtils.getFirstQualifier(calleeReferenceExpr);
+          if (firstQualifier != null) {
+            final PsiReference ref = firstQualifier.getReference();
+            if (ref != null && ref.isReferenceTo(this)) {
+              return null;
+            }
+          }
+        }
         final PyResolveContext resolveContext = PyResolveContext.noImplicits().withTypeEvalContext(context);
         final CallArgumentsMapping mapping = argumentList.analyzeCall(resolveContext);
         for (Map.Entry<PyExpression, PyNamedParameter> entry : mapping.getPlainMappedParams().entrySet()) {
diff --git a/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py b/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py
new file mode 100644
index 000000000000..a91281d759d6
--- /dev/null
+++ b/python/testData/inspections/PyUnresolvedReferencesInspection/baseStringCheck.py
@@ -0,0 +1,4 @@
+def repl(s):
+    if not isinstance(s, basestring):
+        return s
+    return s.replace(s.replace('a', 'b'), s)
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
index 5981c6b74767..1499084c4def 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyUnresolvedReferencesInspectionTest.java
@@ -505,6 +505,11 @@ public class PyUnresolvedReferencesInspectionTest extends PyInspectionTestCase {
     doTest();
   }
 
+  // PY-11541
+  public void testBaseStringCheck() {
+    doTest();
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {