diff --git a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt
index c44343dce77..f9579c02cd2 100644
--- a/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt
+++ b/compiler/fir/fir2ir/src/org/jetbrains/kotlin/fir/backend/Fir2IrVisitor.kt
@@ -1291,13 +1291,13 @@ class Fir2IrVisitor(
     }
 
     private fun FirWhenBranch.toIrWhenBranch(whenExpressionType: ConeKotlinType): IrBranch {
-        return convertWithOffsets { startOffset, endOffset ->
+        return convertWithOffsets { startOffset, _ ->
             val condition = condition
             val irResult = convertToIrExpression(result).insertImplicitCast(result, result.resolvedType, whenExpressionType)
             if (condition is FirElseIfTrueCondition) {
                 IrElseBranchImpl(IrConstImpl.boolean(irResult.startOffset, irResult.endOffset, irBuiltIns.booleanType, true), irResult)
             } else {
-                IrBranchImpl(startOffset, endOffset, convertToIrExpression(condition), irResult)
+                IrBranchImpl(startOffset, irResult.endOffset, convertToIrExpression(condition), irResult)
             }
         }
     }
diff --git a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirLightTreeJvmIrSourceRangesTestGenerated.java b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirLightTreeJvmIrSourceRangesTestGenerated.java
index 8936a6dfcd3..93025489b1b 100644
--- a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirLightTreeJvmIrSourceRangesTestGenerated.java
+++ b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirLightTreeJvmIrSourceRangesTestGenerated.java
@@ -67,6 +67,18 @@ public class FirLightTreeJvmIrSourceRangesTestGenerated extends AbstractFirLight
         runTest("compiler/testData/ir/sourceRanges/kt24258.kt");
     }
 
+    @Test
+    @TestMetadata("kt63779.kt")
+    public void testKt63779() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779.kt");
+    }
+
+    @Test
+    @TestMetadata("kt63779_2.kt")
+    public void testKt63779_2() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779_2.kt");
+    }
+
     @Test
     @TestMetadata("multiLineCall.kt")
     public void testMultiLineCall() throws Exception {
diff --git a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirPsiJvmIrSourceRangesTestGenerated.java b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirPsiJvmIrSourceRangesTestGenerated.java
index 3d7160859ca..6f284c04b2d 100644
--- a/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirPsiJvmIrSourceRangesTestGenerated.java
+++ b/compiler/fir/fir2ir/tests-gen/org/jetbrains/kotlin/test/runners/ir/FirPsiJvmIrSourceRangesTestGenerated.java
@@ -67,6 +67,18 @@ public class FirPsiJvmIrSourceRangesTestGenerated extends AbstractFirPsiJvmIrSou
         runTest("compiler/testData/ir/sourceRanges/kt24258.kt");
     }
 
+    @Test
+    @TestMetadata("kt63779.kt")
+    public void testKt63779() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779.kt");
+    }
+
+    @Test
+    @TestMetadata("kt63779_2.kt")
+    public void testKt63779_2() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779_2.kt");
+    }
+
     @Test
     @TestMetadata("multiLineCall.kt")
     public void testMultiLineCall() throws Exception {
diff --git a/compiler/testData/ir/sourceRanges/kt63779.kt b/compiler/testData/ir/sourceRanges/kt63779.kt
new file mode 100644
index 00000000000..59d58902cb9
--- /dev/null
+++ b/compiler/testData/ir/sourceRanges/kt63779.kt
@@ -0,0 +1,8 @@
+// FIR_IDENTICAL
+
+fun topLevelMethod(x: Int, y: Int) {
+    if(x > y) {
+    } else if(x < y) {
+    } else {
+    }
+}
\ No newline at end of file
diff --git a/compiler/testData/ir/sourceRanges/kt63779.txt b/compiler/testData/ir/sourceRanges/kt63779.txt
new file mode 100644
index 00000000000..8c384a056d3
--- /dev/null
+++ b/compiler/testData/ir/sourceRanges/kt63779.txt
@@ -0,0 +1,19 @@
+@0:0..8:0 FILE fqName:<root> fileName:/kt63779.kt
+  @2:0..7:1 FUN name:topLevelMethod visibility:public modality:FINAL <> (x:kotlin.Int, y:kotlin.Int) returnType:kotlin.Unit
+    @2:19..25 VALUE_PARAMETER name:x index:0 type:kotlin.Int
+    @2:27..33 VALUE_PARAMETER name:y index:1 type:kotlin.Int
+    @2:35..7:1 BLOCK_BODY
+      @3:4..6:5 WHEN type=kotlin.Unit origin=IF
+        @3:7..4:5 BRANCH
+          @3:7..12 CALL 'public final fun greater (arg0: kotlin.Int, arg1: kotlin.Int): kotlin.Boolean declared in kotlin.internal.ir' type=kotlin.Boolean origin=GT
+            @3:7..8 GET_VAR 'x: kotlin.Int declared in <root>.topLevelMethod' type=kotlin.Int origin=null
+            @3:11..12 GET_VAR 'y: kotlin.Int declared in <root>.topLevelMethod' type=kotlin.Int origin=null
+          @3:14..4:5 BLOCK type=kotlin.Unit origin=null
+        @4:14..5:5 BRANCH
+          @4:14..19 CALL 'public final fun less (arg0: kotlin.Int, arg1: kotlin.Int): kotlin.Boolean declared in kotlin.internal.ir' type=kotlin.Boolean origin=LT
+            @4:14..15 GET_VAR 'x: kotlin.Int declared in <root>.topLevelMethod' type=kotlin.Int origin=null
+            @4:18..19 GET_VAR 'y: kotlin.Int declared in <root>.topLevelMethod' type=kotlin.Int origin=null
+          @4:21..5:5 BLOCK type=kotlin.Unit origin=null
+        @5:11..6:5 BRANCH
+          @5:11..6:5 CONST Boolean type=kotlin.Boolean value=true
+          @5:11..6:5 BLOCK type=kotlin.Unit origin=null
diff --git a/compiler/testData/ir/sourceRanges/kt63779_2.fir.txt b/compiler/testData/ir/sourceRanges/kt63779_2.fir.txt
new file mode 100644
index 00000000000..3b9f8a75a95
--- /dev/null
+++ b/compiler/testData/ir/sourceRanges/kt63779_2.fir.txt
@@ -0,0 +1,16 @@
+@0:0..5:0 FILE fqName:<root> fileName:/kt63779_2.kt
+  @1:0..4:1 FUN name:topLevelMethod visibility:public modality:FINAL <> () returnType:kotlin.Unit
+    @1:21..4:1 BLOCK_BODY
+      @2:4..13 VAR name:z type:kotlin.Int [var]
+        @2:12..13 CONST Int type=kotlin.Int value=3
+      @3:4..37 WHEN type=kotlin.Unit origin=IF
+        @3:7..22 BRANCH
+          @3:7..11 CONST Boolean type=kotlin.Boolean value=true
+          @3:13..22 BLOCK type=kotlin.Unit origin=null
+            @3:15..20 SET_VAR 'var z: kotlin.Int [var] declared in <root>.topLevelMethod' type=kotlin.Unit origin=EQ
+              @3:19..20 CONST Int type=kotlin.Int value=4
+        @3:28..37 BRANCH
+          @3:28..37 CONST Boolean type=kotlin.Boolean value=true
+          @3:28..37 BLOCK type=kotlin.Unit origin=null
+            @3:30..35 SET_VAR 'var z: kotlin.Int [var] declared in <root>.topLevelMethod' type=kotlin.Unit origin=EQ
+              @3:34..35 CONST Int type=kotlin.Int value=5
diff --git a/compiler/testData/ir/sourceRanges/kt63779_2.kt b/compiler/testData/ir/sourceRanges/kt63779_2.kt
new file mode 100644
index 00000000000..c5acc0b6c42
--- /dev/null
+++ b/compiler/testData/ir/sourceRanges/kt63779_2.kt
@@ -0,0 +1,5 @@
+// In this test K2 behaviour is preferable.
+fun topLevelMethod() {
+    var z = 3
+    if(true) { z = 4 } else { z = 5 }
+}
diff --git a/compiler/testData/ir/sourceRanges/kt63779_2.txt b/compiler/testData/ir/sourceRanges/kt63779_2.txt
new file mode 100644
index 00000000000..fa07217c518
--- /dev/null
+++ b/compiler/testData/ir/sourceRanges/kt63779_2.txt
@@ -0,0 +1,16 @@
+@0:0..5:0 FILE fqName:<root> fileName:/kt63779_2.kt
+  @1:0..4:1 FUN name:topLevelMethod visibility:public modality:FINAL <> () returnType:kotlin.Unit
+    @1:21..4:1 BLOCK_BODY
+      @2:8..9 VAR name:z type:kotlin.Int [var]
+        @2:12..13 CONST Int type=kotlin.Int value=3
+      @3:4..37 WHEN type=kotlin.Unit origin=IF
+        @3:4..37 BRANCH
+          @3:7..11 CONST Boolean type=kotlin.Boolean value=true
+          @3:13..22 BLOCK type=kotlin.Unit origin=null
+            @3:15..16 SET_VAR 'var z: kotlin.Int [var] declared in <root>.topLevelMethod' type=kotlin.Unit origin=EQ
+              @3:19..20 CONST Int type=kotlin.Int value=4
+        @3:4..37 BRANCH
+          @3:4..37 CONST Boolean type=kotlin.Boolean value=true
+          @3:28..37 BLOCK type=kotlin.Unit origin=null
+            @3:30..31 SET_VAR 'var z: kotlin.Int [var] declared in <root>.topLevelMethod' type=kotlin.Unit origin=EQ
+              @3:34..35 CONST Int type=kotlin.Int value=5
diff --git a/compiler/testData/ir/sourceRanges/this.fir.txt b/compiler/testData/ir/sourceRanges/this.fir.txt
index 1147e5e9abc..9c5dc1d0816 100644
--- a/compiler/testData/ir/sourceRanges/this.fir.txt
+++ b/compiler/testData/ir/sourceRanges/this.fir.txt
@@ -8,7 +8,7 @@
       @3:4..46 FIELD PROPERTY_BACKING_FIELD name:maybeThis type:<root>.Klass? visibility:private [final]
         @3:20..46 EXPRESSION_BODY
           @3:20..46 WHEN type=<root>.Klass? origin=IF
-            @3:24..30 BRANCH
+            @3:24..36 BRANCH
               @3:24..30 CALL 'public final fun EQEQ (arg0: kotlin.Any?, arg1: kotlin.Any?): kotlin.Boolean declared in kotlin.internal.ir' type=kotlin.Boolean origin=EQEQ
                 @3:24..25 CONST Int type=kotlin.Int value=1
                 @3:29..30 CONST Int type=kotlin.Int value=1
diff --git a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/ir/ClassicJvmIrSourceRangesTestGenerated.java b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/ir/ClassicJvmIrSourceRangesTestGenerated.java
index 05d5663a1c6..3de9d48d759 100644
--- a/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/ir/ClassicJvmIrSourceRangesTestGenerated.java
+++ b/compiler/tests-common-new/tests-gen/org/jetbrains/kotlin/test/runners/ir/ClassicJvmIrSourceRangesTestGenerated.java
@@ -67,6 +67,18 @@ public class ClassicJvmIrSourceRangesTestGenerated extends AbstractClassicJvmIrS
         runTest("compiler/testData/ir/sourceRanges/kt24258.kt");
     }
 
+    @Test
+    @TestMetadata("kt63779.kt")
+    public void testKt63779() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779.kt");
+    }
+
+    @Test
+    @TestMetadata("kt63779_2.kt")
+    public void testKt63779_2() throws Exception {
+        runTest("compiler/testData/ir/sourceRanges/kt63779_2.kt");
+    }
+
     @Test
     @TestMetadata("multiLineCall.kt")
     public void testMultiLineCall() throws Exception {