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 5df6e2371..01ad4c6be 100644
--- a/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java
+++ b/teavm-core/src/main/java/org/teavm/debugging/DebugInformationBuilder.java
@@ -63,11 +63,11 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
         debugInformation = null;
         int fileIndex = files.index(fileName);
         if (!Objects.equals(currentFileName, fileName)) {
-            fileMapping.add(locationProvider, fileIndex);
+            fileMapping.add(locationProvider, fileIndex, true);
             currentFileName = fileName;
         }
         if (currentLine != line) {
-            lineMapping.add(locationProvider, line);
+            lineMapping.add(locationProvider, line, true);
             currentLine = line;
         }
     }
@@ -77,7 +77,7 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
         debugInformation = null;
         int classIndex = classes.index(className);
         if (!Objects.equals(className, currentClass)) {
-            classMapping.add(locationProvider, classIndex);
+            classMapping.add(locationProvider, classIndex, true);
             currentClass = className;
         }
     }
@@ -87,7 +87,7 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
         debugInformation = null;
         int methodIndex = methods.index(method != null ? method.toString() : null);
         if (!Objects.equals(method, currentMethod)) {
-            methodMapping.add(locationProvider, methodIndex);
+            methodMapping.add(locationProvider, methodIndex, true);
             currentMethod = method;
         }
         if (currentClass != null) {
@@ -133,13 +133,13 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
                 callSiteMapping.values.set(index, exactMethodIndex);
             }
         };
-        callSiteMapping.add(locationProvider, -1);
+        callSiteMapping.add(locationProvider, -1, false);
         return callSite;
     }
 
     @Override
     public void emitEmptyCallSite() {
-        callSiteMapping.add(locationProvider, -1);
+        callSiteMapping.add(locationProvider, -1, false);
     }
 
     @Override
@@ -238,8 +238,8 @@ public class DebugInformationBuilder implements DebugInformationEmitter {
         IntegerArray columns = new IntegerArray(1);
         IntegerArray values = new IntegerArray(1);
 
-        public void add(LocationProvider location, int value) {
-            if (lines.size() > 1) {
+        public void add(LocationProvider location, int value, boolean merge) {
+            if (merge && lines.size() > 1) {
                 int last = lines.size() - 1;
                 if (lines.get(last) == location.getLine() && columns.get(last) == location.getColumn()) {
                     values.set(last, value);
diff --git a/teavm-core/src/main/java/org/teavm/debugging/Debugger.java b/teavm-core/src/main/java/org/teavm/debugging/Debugger.java
index 7173a29b4..4aa568231 100644
--- a/teavm-core/src/main/java/org/teavm/debugging/Debugger.java
+++ b/teavm-core/src/main/java/org/teavm/debugging/Debugger.java
@@ -74,43 +74,40 @@ public class Debugger {
         step(false);
     }
 
+    private void jsStep(boolean enterMethod) {
+        if (enterMethod) {
+            javaScriptDebugger.stepInto();
+        } else {
+            javaScriptDebugger.stepOver();
+        }
+    }
+
     private void step(boolean enterMethod) {
         CallFrame[] callStack = getCallStack();
         if (callStack == null || callStack.length == 0) {
-            if (enterMethod) {
-                javaScriptDebugger.stepInto();
-            } else {
-                javaScriptDebugger.stepOver();
-            }
+            jsStep(enterMethod);
             return;
         }
         CallFrame recentFrame = callStack[0];
         if (recentFrame.getLocation() == null || recentFrame.getLocation().getFileName() == null ||
                 recentFrame.getLocation().getLine() < 0) {
-            if (enterMethod) {
-                javaScriptDebugger.stepInto();
-            } else {
-                javaScriptDebugger.stepOver();
-            }
+            jsStep(enterMethod);
             return;
         }
         Set<JavaScriptLocation> successors = new HashSet<>();
-        for (int i = 0; i < callStack.length; ++i) {
-            CallFrame frame = callStack[i];
-            boolean exits = false;
-            DebugInformation mainDebugInfo = debugInformationMap.get(frame.originalLocation.getScript());
+        for (CallFrame frame : callStack) {
+            boolean exits;
+            String script = frame.originalLocation.getScript();
             GeneratedLocation genLoc = new GeneratedLocation(frame.originalLocation.getLine(),
                     frame.originalLocation.getColumn());
-            MethodReference callMethod = null;
-            if (mainDebugInfo != null) {
-                GeneratedLocation callSiteLoc = mainDebugInfo.getNearestCallSite(genLoc);
-                if (callSiteLoc != null) {
-                    callMethod = mainDebugInfo.getCallSite(callSiteLoc);
-                }
-            }
-            String script = frame.originalLocation.getScript();
             DebugInformation debugInfo = debugInformationMap.get(script);
-            if (debugInfo != null) {
+            if (frame.getLocation() != null && debugInfo != null) {
+                exits = false;
+                MethodReference callMethod = null;
+                GeneratedLocation callSiteLoc = debugInfo.getNearestCallSite(genLoc);
+                if (callSiteLoc != null) {
+                    callMethod = debugInfo.getCallSite(callSiteLoc);
+                }
                 SourceLocation[] following = debugInfo.getFollowingLines(frame.getLocation());
                 if (following != null) {
                     for (SourceLocation successor : following) {
@@ -130,6 +127,8 @@ public class Debugger {
                         }
                     }
                 }
+            } else {
+                exits = true;
             }
             if (!exits) {
                 break;
diff --git a/teavm-core/src/main/java/org/teavm/debugging/JavaScriptLocation.java b/teavm-core/src/main/java/org/teavm/debugging/JavaScriptLocation.java
index 0bb830ac3..45dc1e24a 100644
--- a/teavm-core/src/main/java/org/teavm/debugging/JavaScriptLocation.java
+++ b/teavm-core/src/main/java/org/teavm/debugging/JavaScriptLocation.java
@@ -53,12 +53,12 @@ public class JavaScriptLocation {
             return false;
         }
         JavaScriptLocation other = (JavaScriptLocation)obj;
-        return Objects.equals(other.script, script) && other.line == line;
+        return Objects.equals(other.script, script) && other.line == line && other.column == column;
     }
 
     @Override
     public int hashCode() {
-        return (31 + line) * 31 + Objects.hashCode(script);
+        return (31 + column) * ((31 + line) * 31 + Objects.hashCode(script));
     }
 
     @Override