diff --git a/teavm-core/src/main/java/org/teavm/debugging/DebugInformation.java b/teavm-core/src/main/java/org/teavm/debugging/DebugInformation.java
index 8d9e914c9..aeed36f18 100644
--- a/teavm-core/src/main/java/org/teavm/debugging/DebugInformation.java
+++ b/teavm-core/src/main/java/org/teavm/debugging/DebugInformation.java
@@ -325,10 +325,9 @@ public class DebugInformation {
         FileDescription build() {
             FileDescription description = new FileDescription();
             description.generatedLocationData = new int[generatedLocationData.size()];
-            description.generatedLocationStart = new int[generatedLocationStart.size()];
+            description.generatedLocationStart = new int[generatedLocationStart.size() + 1];
             int current = 0;
             for (int i = 0; i < generatedLocationStart.size(); ++i) {
-                description.generatedLocationStart[i] = current;
                 current += generatedLocationSize.get(i) * 2;
                 int j = current;
                 int ptr = generatedLocationStart.get(i);
@@ -336,6 +335,7 @@ public class DebugInformation {
                     description.generatedLocationData[--j] = generatedLocationData.get(ptr);
                     ptr = generatedLocationPointers.get(ptr);
                 }
+                description.generatedLocationStart[i + 1] = current;
             }
             return description;
         }
diff --git a/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java b/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java
index 743ec5514..c69fb4b8f 100644
--- a/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java
+++ b/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java
@@ -348,7 +348,7 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
                 IntegerArray linesChunk = new IntegerArray(1);
                 IntegerArray filesChunk = new IntegerArray(1);
                 int ptr = start.get(i);
-                while (ptr > 0) {
+                while (ptr >= 0) {
                     linesChunk.add(lines.get(ptr));
                     filesChunk.add(files.get(ptr));
                     ptr = next.get(ptr);
@@ -361,7 +361,7 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
                 int distinctSize = 0;
                 for (int j = 0; j < pairs.length; ++j) {
                     long pair = pairs[j];
-                    if (distinctSize == 0 || pair != pairs[distinctSize]) {
+                    if (distinctSize == 0 || pair != pairs[distinctSize - 1]) {
                         pairs[distinctSize++] = pair;
                         filesData.add((int)(pair >>> 32));
                         linesData.add((int)pair);
diff --git a/teavm-core/src/main/java/org/teavm/model/util/ListingBuilder.java b/teavm-core/src/main/java/org/teavm/model/util/ListingBuilder.java
index d32a5e82a..c7d0852f3 100644
--- a/teavm-core/src/main/java/org/teavm/model/util/ListingBuilder.java
+++ b/teavm-core/src/main/java/org/teavm/model/util/ListingBuilder.java
@@ -16,6 +16,7 @@
 package org.teavm.model.util;
 
 import java.util.List;
+import java.util.Objects;
 import org.teavm.model.*;
 
 /**
@@ -25,7 +26,8 @@ import org.teavm.model.*;
 public class ListingBuilder {
     public String buildListing(ProgramReader program, String prefix) {
         StringBuilder sb = new StringBuilder();
-        InstructionStringifier stringifier = new InstructionStringifier(sb);
+        StringBuilder insnSb = new StringBuilder();
+        InstructionStringifier stringifier = new InstructionStringifier(insnSb);
         for (int i = 0; i < program.variableCount(); ++i) {
             sb.append(prefix).append("var @").append(i);
             VariableReader var = program.variableAt(i);
@@ -59,10 +61,16 @@ public class ListingBuilder {
                 }
                 sb.append("\n");
             }
+            InstructionLocation location = null;
             for (int j = 0; j < block.instructionCount(); ++j) {
-                sb.append(prefix).append("    ");
+                insnSb.setLength(0);
                 block.readInstruction(j, stringifier);
-                sb.append("\n");
+                if (!Objects.equals(location, stringifier.getLocation())) {
+                    location = stringifier.getLocation();
+                    sb.append(prefix).append("  at ").append(location != null ? location.toString() :
+                            "unknown location").append('\n');
+                }
+                sb.append(prefix).append("    ").append(insnSb).append("\n");
             }
             for (TryCatchBlockReader tryCatch : block.readTryCatchBlocks()) {
                 sb.append(prefix).append("    catch ").append(tryCatch.getExceptionType()).append(" @")