diff --git a/idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/intentions/WhenToIfIntention.kt b/idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/intentions/WhenToIfIntention.kt
index 008bc3c2eed..cdb4a518c98 100644
--- a/idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/intentions/WhenToIfIntention.kt
+++ b/idea/src/org/jetbrains/kotlin/idea/intentions/branchedTransformations/intentions/WhenToIfIntention.kt
@@ -22,6 +22,7 @@ import com.intellij.openapi.util.TextRange
 import org.jetbrains.kotlin.idea.intentions.SelfTargetingRangeIntention
 import org.jetbrains.kotlin.idea.intentions.branchedTransformations.combineWhenConditions
 import org.jetbrains.kotlin.idea.util.CommentSaver
+import org.jetbrains.kotlin.psi.KtIfExpression
 import org.jetbrains.kotlin.psi.KtPsiFactory
 import org.jetbrains.kotlin.psi.KtWhenExpression
 import org.jetbrains.kotlin.psi.buildExpression
@@ -54,7 +55,13 @@ class WhenToIfIntention : SelfTargetingRangeIntention<KtWhenExpression>(KtWhenEx
                     appendFixedText("if (")
                     appendExpression(condition)
                     appendFixedText(")")
+                    if (branch is KtIfExpression) {
+                        appendFixedText("{ ")
+                    }
                     appendExpression(branch)
+                    if (branch is KtIfExpression) {
+                        appendFixedText(" }")
+                    }
                 }
                 if (i != entries.lastIndex) {
                     appendFixedText("\n")
diff --git a/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt b/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt
new file mode 100644
index 00000000000..42dce20f3d2
--- /dev/null
+++ b/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt
@@ -0,0 +1,11 @@
+// KT-12942: when to if changes semantics
+fun test(b: Boolean): String {
+    <caret>when (b) {
+        true ->
+            if (true) return "first"
+        false ->
+            if (true) return "second"
+    }
+
+    return "none"
+}
\ No newline at end of file
diff --git a/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt.after b/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt.after
new file mode 100644
index 00000000000..9aa8bfea32c
--- /dev/null
+++ b/idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt.after
@@ -0,0 +1,10 @@
+// KT-12942: when to if changes semantics
+fun test(b: Boolean): String {
+    if (b == true) {
+        if (true) return "first"
+    } else if (b == false) {
+        if (true) return "second"
+    }
+
+    return "none"
+}
\ No newline at end of file
diff --git a/idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java b/idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java
index ea01b78300e..e8f0832e0d1 100644
--- a/idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java
+++ b/idea/tests/org/jetbrains/kotlin/idea/intentions/IntentionTestGenerated.java
@@ -1711,6 +1711,12 @@ public class IntentionTestGenerated extends AbstractIntentionTest {
                     doTest(fileName);
                 }
 
+                @TestMetadata("whenWithIf.kt")
+                public void testWhenWithIf() throws Exception {
+                    String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/branched/ifWhen/whenToIf/whenWithIf.kt");
+                    doTest(fileName);
+                }
+
                 @TestMetadata("whenWithMultiConditions.kt")
                 public void testWhenWithMultiConditions() throws Exception {
                     String fileName = KotlinTestUtils.navigationMetadata("idea/testData/intentions/branched/ifWhen/whenToIf/whenWithMultiConditions.kt");