diff --git a/core/src/main/java/org/teavm/model/Variable.java b/core/src/main/java/org/teavm/model/Variable.java
index e9de49fc3..d3262daf6 100644
--- a/core/src/main/java/org/teavm/model/Variable.java
+++ b/core/src/main/java/org/teavm/model/Variable.java
@@ -70,4 +70,8 @@ public class Variable implements VariableReader {
     public void setLabel(String label) {
         this.label = label;
     }
+
+    public String getDisplayLabel() {
+        return label != null ? label : String.valueOf(index);
+    }
 }
diff --git a/core/src/main/java/org/teavm/model/analysis/NullnessInformationBuilder.java b/core/src/main/java/org/teavm/model/analysis/NullnessInformationBuilder.java
index 8742c381f..90f53c718 100644
--- a/core/src/main/java/org/teavm/model/analysis/NullnessInformationBuilder.java
+++ b/core/src/main/java/org/teavm/model/analysis/NullnessInformationBuilder.java
@@ -84,9 +84,9 @@ class NullnessInformationBuilder {
     }
 
     private void extendProgram() {
+        notNullVariables.set(0);
         insertAdditionalVariables();
 
-        notNullVariables.set(0);
         Variable[] parameters = new Variable[methodDescriptor.parameterCount() + 1];
         for (int i = 0; i < parameters.length; ++i) {
             parameters[i] = program.variableAt(i);
@@ -123,7 +123,7 @@ class NullnessInformationBuilder {
         for (BasicBlock block : program.getBasicBlocks()) {
             for (Phi phi : block.getPhis()) {
                 for (Incoming incoming : phi.getIncomings()) {
-                    builder.addEdge(incoming.getSource().getIndex(), phi.getReceiver().getIndex());
+                    builder.addEdge(incoming.getValue().getIndex(), phi.getReceiver().getIndex());
                 }
             }
             for (TryCatchBlock tryCatch : block.getTryCatchBlocks()) {
@@ -183,6 +183,7 @@ class NullnessInformationBuilder {
                 continue;
             }
             visited[node] = true;
+            notNullVariables.set(node);
             for (int successor : assignmentGraph.outgoingEdges(node)) {
                 if (sccIndexes[successor] == 0 || sccIndexes[successor] != sccIndexes[node]) {
                     if (--notNullPredecessorsLeft[successor] == 0) {
@@ -203,6 +204,10 @@ class NullnessInformationBuilder {
         public State visit(BasicBlock block) {
             currentState = new State();
 
+            if (block.getExceptionVariable() != null) {
+                notNullVariables.set(block.getIndex());
+            }
+
             currentBlock = block;
             if (nullSuccessors.containsKey(block.getIndex())) {
                 int varIndex = nullSuccessors.remove(block.getIndex());
diff --git a/core/src/main/java/org/teavm/model/util/PhiUpdater.java b/core/src/main/java/org/teavm/model/util/PhiUpdater.java
index 180aae46a..b58804719 100644
--- a/core/src/main/java/org/teavm/model/util/PhiUpdater.java
+++ b/core/src/main/java/org/teavm/model/util/PhiUpdater.java
@@ -488,7 +488,7 @@ public class PhiUpdater {
     private Variable use(Variable var) {
         Variable mappedVar = variableMap[var.getIndex()];
         if (mappedVar == null) {
-            throw new AssertionError("Variable used before definition: " + var.getIndex());
+            throw new AssertionError("Variable used before definition: " + var.getDisplayLabel());
         }
         usedPhis.set(mappedVar.getIndex());
         return mappedVar;
diff --git a/core/src/test/java/org/teavm/model/analysis/test/NullnessAnalysisTest.java b/core/src/test/java/org/teavm/model/analysis/test/NullnessAnalysisTest.java
index 19232f6cf..9aee7278b 100644
--- a/core/src/test/java/org/teavm/model/analysis/test/NullnessAnalysisTest.java
+++ b/core/src/test/java/org/teavm/model/analysis/test/NullnessAnalysisTest.java
@@ -60,6 +60,21 @@ public class NullnessAnalysisTest {
         test();
     }
 
+    @Test
+    public void phiPropagation() {
+        test();
+    }
+
+    @Test
+    public void tryCatchJoint() {
+        test();
+    }
+
+    @Test
+    public void loop() {
+        test();
+    }
+
     private void test() {
         String baseName = "model/analysis/nullness/" + name.getMethodName();
         String originalResourceName = baseName + ".original.txt";
diff --git a/core/src/test/resources/model/analysis/nullness/loop.extended.txt b/core/src/test/resources/model/analysis/nullness/loop.extended.txt
new file mode 100644
index 000000000..36ec8446a
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/loop.extended.txt
@@ -0,0 +1,21 @@
+var @this as this
+
+$start
+    @first := field `Foo.first` @this as `LBar;`
+    @checkedFirst := nullCheck @first
+    goto $head
+$head
+    @current := phi @checkedFirst from $start, @checkedNext from $body
+    @isLast := field `Bar.last` @current as Z
+    @current_2 := nullCheck @current
+    if @isLast == 0 then goto $exit else goto $body
+$body
+    @next := field `Bar.next` @current_2 as `LBar;`
+    @checkedNext := nullCheck @next
+    goto $head
+$exit
+    @value := field `Bar.value` @current_2 as `Ljava/lang/Object;`
+    return @value
+
+// NOT_NULL current
+// NOT_NULL current_2
diff --git a/core/src/test/resources/model/analysis/nullness/loop.original.txt b/core/src/test/resources/model/analysis/nullness/loop.original.txt
new file mode 100644
index 000000000..09cb0f4ea
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/loop.original.txt
@@ -0,0 +1,17 @@
+var @this as this
+
+$start
+    @first := field `Foo.first` @this as `LBar;`
+    @checkedFirst := nullCheck @first
+    goto $head
+$head
+    @current := phi @checkedFirst from $start, @checkedNext from $body
+    @isLast := field `Bar.last` @current as Z
+    if @isLast == 0 then goto $exit else goto $body
+$body
+    @next := field `Bar.next` @current as `LBar;`
+    @checkedNext := nullCheck @next
+    goto $head
+$exit
+    @value := field `Bar.value` @current as `Ljava/lang/Object;`
+    return @value
\ No newline at end of file
diff --git a/core/src/test/resources/model/analysis/nullness/phiJoin.extended.txt b/core/src/test/resources/model/analysis/nullness/phiJoin.extended.txt
index 6417695ba..dff4d52b8 100644
--- a/core/src/test/resources/model/analysis/nullness/phiJoin.extended.txt
+++ b/core/src/test/resources/model/analysis/nullness/phiJoin.extended.txt
@@ -1,4 +1,7 @@
+var @this as this
+
 $start
+    @cond := invokeStatic `Cond.get()Ljava/lang/Object;`
     if @cond === null then goto $ifNull else goto $ifNotNull
 $ifNull
     @cond_1 := null
@@ -14,8 +17,8 @@ $join
     @d := phi @a from $ifNull, @b_1 from $ifNotNull
     return @c
 
-// NULLABLE: b
-// NOT_NULL: b_1
-// NOT_NULL: a
-// NULLABLE: c
-// NOT_NULL: d
\ No newline at end of file
+// NULLABLE b
+// NOT_NULL b_1
+// NOT_NULL a
+// NULLABLE c
+// NOT_NULL d
\ No newline at end of file
diff --git a/core/src/test/resources/model/analysis/nullness/phiJoin.original.txt b/core/src/test/resources/model/analysis/nullness/phiJoin.original.txt
index bd0642292..62ce89a93 100644
--- a/core/src/test/resources/model/analysis/nullness/phiJoin.original.txt
+++ b/core/src/test/resources/model/analysis/nullness/phiJoin.original.txt
@@ -1,4 +1,7 @@
+var @this as this
+
 $start
+    @cond := invokeStatic `Cond.get()Ljava/lang/Object;`
     if @cond === null then goto $ifNull else goto $ifNotNull
 $ifNull
     @a := 'qwe'
diff --git a/core/src/test/resources/model/analysis/nullness/phiPropagation.extended.txt b/core/src/test/resources/model/analysis/nullness/phiPropagation.extended.txt
new file mode 100644
index 000000000..6d97f4ba7
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/phiPropagation.extended.txt
@@ -0,0 +1,27 @@
+var @this as this
+
+$start
+    @a := invokeStatic `Value.extract()Ljava/lang/String;`
+    @cond := invokeStatic `Cond.invoke()I`
+    if @cond == 0 then goto $if0 else goto $else
+$if0
+    @len := invokeStatic `Value.extractLen()I`
+    if @len == 0 then goto $ifEmpty else goto $ifNotEmpty
+$ifEmpty
+    invokeStatic `Foo.f(Ljava/lang/String;)V` @a
+    goto $joinIf0
+$ifNotEmpty
+    invokeVirtual `java.lang.String.trim()Ljava/lang/String;` @a
+    @a_1 := nullCheck @a
+    goto $joinIf0
+$joinIf0
+    @a_2 := phi @a from $ifEmpty, @a_1 from $ifNotEmpty
+    invokeStatic `Foo.g(Ljava/lang/String;)V` @a_2
+    goto $join
+$else
+    invokeStatic `Foo.bar(Ljava/lang/String;)V` @a
+    goto $join
+$join
+    @a_3 := phi @a_2 from $joinIf0, @a from $else
+    invokeStatic `Foo.baz(Ljava/lang/String;)V` @a_3
+    return
\ No newline at end of file
diff --git a/core/src/test/resources/model/analysis/nullness/phiPropagation.original.txt b/core/src/test/resources/model/analysis/nullness/phiPropagation.original.txt
new file mode 100644
index 000000000..9b0408273
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/phiPropagation.original.txt
@@ -0,0 +1,24 @@
+var @this as this
+
+$start
+    @a := invokeStatic `Value.extract()Ljava/lang/String;`
+    @cond := invokeStatic `Cond.invoke()I`
+    if @cond == 0 then goto $if0 else goto $else
+$if0
+    @len := invokeStatic `Value.extractLen()I`
+    if @len == 0 then goto $ifEmpty else goto $ifNotEmpty
+$ifEmpty
+    invokeStatic `Foo.f(Ljava/lang/String;)V` @a
+    goto $joinIf0
+$ifNotEmpty
+    invokeVirtual `java.lang.String.trim()Ljava/lang/String;` @a
+    goto $joinIf0
+$joinIf0
+    invokeStatic `Foo.g(Ljava/lang/String;)V` @a
+    goto $join
+$else
+    invokeStatic `Foo.bar(Ljava/lang/String;)V` @a
+    goto $join
+$join
+    invokeStatic `Foo.baz(Ljava/lang/String;)V` @a
+    return
\ No newline at end of file
diff --git a/core/src/test/resources/model/analysis/nullness/tryCatchJoint.extended.txt b/core/src/test/resources/model/analysis/nullness/tryCatchJoint.extended.txt
new file mode 100644
index 000000000..a8bad3c1e
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/tryCatchJoint.extended.txt
@@ -0,0 +1,29 @@
+var @this as this
+
+$start
+    @bar := invokeVirtual `Foo.bar()LBar;` @this
+    @cond := invokeVirtual `Foo.cond()I` @this
+    if @cond == 0 then goto $if0 else goto $else
+$if0
+    invokeVirtual `Bar.baz()LBar;` @bar
+    @bar_1 := nullCheck @bar
+    goto $join
+catch java.lang.RuntimeException goto $if0Handler
+    @bar_2 := ephi @bar, @bar_1
+$if0Handler
+    goto $join
+$else
+    invokeVirtual `Bar.baz()LBar;` @bar
+    @bar_3 := nullCheck @bar
+    goto $else1
+$else1
+    invokeVirtual `Bar.baz2()LBar;` @bar_3
+    goto $join
+catch java.lang.RuntimeException goto $elseHandler
+$elseHandler
+    goto $join
+$join
+    @bar_4 := phi @bar_1 from $if0, @bar_2 from $if0Handler, @bar_3 from $else1, @bar_3 from $elseHandler
+    return @bar_4
+
+// NULLABLE bar_2
\ No newline at end of file
diff --git a/core/src/test/resources/model/analysis/nullness/tryCatchJoint.original.txt b/core/src/test/resources/model/analysis/nullness/tryCatchJoint.original.txt
new file mode 100644
index 000000000..20a724067
--- /dev/null
+++ b/core/src/test/resources/model/analysis/nullness/tryCatchJoint.original.txt
@@ -0,0 +1,23 @@
+var @this as this
+
+$start
+    @bar := invokeVirtual `Foo.bar()LBar;` @this
+    @cond := invokeVirtual `Foo.cond()I` @this
+    if @cond == 0 then goto $if0 else goto $else
+$if0
+    invokeVirtual `Bar.baz()LBar;` @bar
+    goto $join
+catch java.lang.RuntimeException goto $if0Handler
+$if0Handler
+    goto $join
+$else
+    invokeVirtual `Bar.baz()LBar;` @bar
+    goto $else1
+$else1
+    invokeVirtual `Bar.baz2()LBar;` @bar
+    goto $join
+catch java.lang.RuntimeException goto $elseHandler
+$elseHandler
+    goto $join
+$join
+    return @bar
\ No newline at end of file