diff --git a/python/src/com/jetbrains/python/codeInsight/PySubstitutionChunkReference.java b/python/src/com/jetbrains/python/codeInsight/PySubstitutionChunkReference.java
index e66921b4ad00..23b54b8eaa3e 100644
--- a/python/src/com/jetbrains/python/codeInsight/PySubstitutionChunkReference.java
+++ b/python/src/com/jetbrains/python/codeInsight/PySubstitutionChunkReference.java
@@ -395,8 +395,8 @@ public class PySubstitutionChunkReference extends PsiReferenceBase<PyStringLiter
   private PyExpression resolveKeywordPercent(@NotNull PyExpression expression, @NotNull String key) {
     final PyExpression containedExpr = PyPsiUtils.flattenParens(expression);
     final PyResolveContext resolveContext = PyResolveContext.noImplicits().withTypeEvalContext(myTypeEvalContext);
-    if (containedExpr instanceof PyDictLiteralExpression) {
-      final Ref<PyExpression> resolvedRef = getElementFromDictLiteral((PyDictLiteralExpression)containedExpr, key, resolveContext);
+    if (PyUtil.instanceOf(containedExpr, PyDictLiteralExpression.class, PyCallExpression.class)) {
+      final Ref<PyExpression> resolvedRef = getElementFromDictLiteral(containedExpr, key, resolveContext);
       return resolvedRef != null ? resolvedRef.get() : containedExpr;
     }
     else if (PyUtil.instanceOf(containedExpr, PyLiteralExpression.class, PySetLiteralExpression.class,
@@ -457,7 +457,6 @@ public class PySubstitutionChunkReference extends PsiReferenceBase<PyStringLiter
     return containedExpression;
   }
 
-
   @Nullable
   private static PyArgumentList getArgumentList(final PsiElement original) {
     final PsiElement pyReferenceExpression = PsiTreeUtil.getParentOfType(original, PyReferenceExpression.class);
diff --git a/python/testData/inspections/PyStringFormatInspection/PackedDictCallUnusedMappingKey.py b/python/testData/inspections/PyStringFormatInspection/PackedDictCallUnusedMappingKey.py
new file mode 100644
index 000000000000..098e0d229a70
--- /dev/null
+++ b/python/testData/inspections/PyStringFormatInspection/PackedDictCallUnusedMappingKey.py
@@ -0,0 +1 @@
+<warning descr="Mapping key \"third\" is unused">'{first}, {second}, {third}'</warning>.format(**dict(first='a', second='b'))
\ No newline at end of file
diff --git a/python/testSrc/com/jetbrains/python/PyResolveTest.java b/python/testSrc/com/jetbrains/python/PyResolveTest.java
index e52d361b4413..0cbf3392e7fd 100644
--- a/python/testSrc/com/jetbrains/python/PyResolveTest.java
+++ b/python/testSrc/com/jetbrains/python/PyResolveTest.java
@@ -719,7 +719,7 @@ public class PyResolveTest extends PyResolveTestCase {
   //PY-2748
   public void testFormatStringPackedDictCall() {
     PsiElement target = resolve();
-    assertInstanceOf(target, PyStarArgument.class);
+    assertInstanceOf(target, PyKeywordArgument.class);
   }
 
   //PY-2748
diff --git a/python/testSrc/com/jetbrains/python/inspections/PyStringFormatInspectionTest.java b/python/testSrc/com/jetbrains/python/inspections/PyStringFormatInspectionTest.java
index 56805529d3bc..b14a3df62414 100644
--- a/python/testSrc/com/jetbrains/python/inspections/PyStringFormatInspectionTest.java
+++ b/python/testSrc/com/jetbrains/python/inspections/PyStringFormatInspectionTest.java
@@ -208,6 +208,11 @@ public class PyStringFormatInspectionTest extends PyTestCase {
   public void testPackedStringTooFewArguments() {
     doTest();
   }
+  
+  // PY-21156
+  public void testPackedDictCallUnusedMappingKey() {
+    doTest();
+  }
 
   private void doTest() {
     myFixture.configureByFile(TEST_DIRECTORY + getTestName(false) + ".py");