diff --git a/core/src/main/java/org/teavm/model/analysis/NullnessChecker.java b/core/src/main/java/org/teavm/model/analysis/NullnessChecker.java
index 09397bd06..152c2ef29 100644
--- a/core/src/main/java/org/teavm/model/analysis/NullnessChecker.java
+++ b/core/src/main/java/org/teavm/model/analysis/NullnessChecker.java
@@ -51,7 +51,7 @@ public class NullnessChecker {
         notNullIncomings = new HashSet<>();
         notNull = new boolean[program.variableCount()];
         nullLiteral = new boolean[program.variableCount()];
-        phiOutputs = ProgramUtils.getPhiOutputs(program);
+        phiOutputs = ProgramUtils.getPhiOutputsByVariable(program);
         graphBuilder = new GraphBuilder(program.variableCount());
 
         Graph cfg = ProgramUtils.buildControlFlowGraph(program);
diff --git a/core/src/main/java/org/teavm/model/optimization/LoopInvariantAnalyzer.java b/core/src/main/java/org/teavm/model/optimization/LoopInvariantAnalyzer.java
index 4fd6846fc..2b757b8cb 100644
--- a/core/src/main/java/org/teavm/model/optimization/LoopInvariantAnalyzer.java
+++ b/core/src/main/java/org/teavm/model/optimization/LoopInvariantAnalyzer.java
@@ -57,10 +57,15 @@ import org.teavm.model.instructions.SwitchInstruction;
 import org.teavm.model.instructions.UnwrapArrayInstruction;
 
 public class LoopInvariantAnalyzer implements InstructionVisitor {
+    private boolean[] notNull;
     public boolean canMove;
     public boolean constant;
     public boolean sideEffect;
 
+    public LoopInvariantAnalyzer(boolean[] notNull) {
+        this.notNull = notNull;
+    }
+
     public void reset() {
         canMove = false;
         constant = false;
@@ -187,7 +192,9 @@ public class LoopInvariantAnalyzer implements InstructionVisitor {
     @Override
     public void visit(ArrayLengthInstruction insn) {
         canMove = true;
-        sideEffect = true;
+        if (!notNull[insn.getArray().getIndex()]) {
+            sideEffect = true;
+        }
     }
 
     @Override
@@ -197,7 +204,9 @@ public class LoopInvariantAnalyzer implements InstructionVisitor {
     @Override
     public void visit(UnwrapArrayInstruction insn) {
         canMove = true;
-        sideEffect = true;
+        if (!notNull[insn.getArray().getIndex()]) {
+            sideEffect = true;
+        }
     }
 
     @Override
@@ -228,16 +237,16 @@ public class LoopInvariantAnalyzer implements InstructionVisitor {
     @Override
     public void visit(NullCheckInstruction insn) {
         canMove = true;
-        sideEffect = true;
+        if (!notNull[insn.getValue().getIndex()]) {
+            sideEffect = true;
+        }
     }
 
     @Override
     public void visit(MonitorEnterInstruction insn) {
-
     }
 
     @Override
     public void visit(MonitorExitInstruction insn) {
-
     }
 }
diff --git a/core/src/main/java/org/teavm/model/optimization/LoopInvariantMotion.java b/core/src/main/java/org/teavm/model/optimization/LoopInvariantMotion.java
index ef2465a51..e6ce37134 100644
--- a/core/src/main/java/org/teavm/model/optimization/LoopInvariantMotion.java
+++ b/core/src/main/java/org/teavm/model/optimization/LoopInvariantMotion.java
@@ -20,6 +20,7 @@ import java.util.Arrays;
 import java.util.List;
 import org.teavm.common.*;
 import org.teavm.model.*;
+import org.teavm.model.analysis.NullnessChecker;
 import org.teavm.model.instructions.*;
 import org.teavm.model.util.*;
 
@@ -53,7 +54,7 @@ public class LoopInvariantMotion implements MethodOptimization {
 
         DefinitionExtractor defExtractor = new DefinitionExtractor();
         UsageExtractor useExtractor = new UsageExtractor();
-        LoopInvariantAnalyzer analyzer = new LoopInvariantAnalyzer();
+        LoopInvariantAnalyzer analyzer = new LoopInvariantAnalyzer(new NullnessChecker().check(program));
         CopyConstantVisitor constantCopier = new CopyConstantVisitor();
         int[][] loopExits = ControlFlowUtils.findLoopExits(graph);
 
diff --git a/core/src/main/java/org/teavm/model/optimization/LoopInversionImpl.java b/core/src/main/java/org/teavm/model/optimization/LoopInversionImpl.java
index d3404c6f9..cc2878753 100644
--- a/core/src/main/java/org/teavm/model/optimization/LoopInversionImpl.java
+++ b/core/src/main/java/org/teavm/model/optimization/LoopInversionImpl.java
@@ -41,6 +41,7 @@ import org.teavm.model.Program;
 import org.teavm.model.TryCatchBlock;
 import org.teavm.model.TryCatchJoint;
 import org.teavm.model.Variable;
+import org.teavm.model.analysis.NullnessChecker;
 import org.teavm.model.util.BasicBlockMapper;
 import org.teavm.model.util.DefinitionExtractor;
 import org.teavm.model.util.InstructionCopyReader;
@@ -222,7 +223,8 @@ class LoopInversionImpl {
         private boolean isInversionProfitable(IntSet nodesToCopy) {
             UsageExtractor useExtractor = new UsageExtractor();
             DefinitionExtractor defExtractor = new DefinitionExtractor();
-            LoopInvariantAnalyzer invariantAnalyzer = new LoopInvariantAnalyzer();
+            boolean[] notNull = new NullnessChecker().check(program);
+            LoopInvariantAnalyzer invariantAnalyzer = new LoopInvariantAnalyzer(notNull);
             for (int node : nodes.toArray()) {
                 if (nodesToCopy.contains(node)) {
                     continue;
diff --git a/core/src/main/java/org/teavm/model/util/ProgramUtils.java b/core/src/main/java/org/teavm/model/util/ProgramUtils.java
index c7cfb237e..d8ae03473 100644
--- a/core/src/main/java/org/teavm/model/util/ProgramUtils.java
+++ b/core/src/main/java/org/teavm/model/util/ProgramUtils.java
@@ -163,6 +163,23 @@ public final class ProgramUtils {
         return outputs;
     }
 
+    public static List<List<Incoming>> getPhiOutputsByVariable(Program program) {
+        List<List<Incoming>> outputs = new ArrayList<>(program.variableCount());
+        for (int i = 0; i < program.variableCount(); ++i) {
+            outputs.add(new ArrayList<>());
+        }
+
+        for (BasicBlock block : program.getBasicBlocks()) {
+            for (Phi phi : block.getPhis()) {
+                for (Incoming incoming : phi.getIncomings()) {
+                    outputs.get(incoming.getValue().getIndex()).add(incoming);
+                }
+            }
+        }
+
+        return outputs;
+    }
+
     public static BasicBlock[] getVariableDefinitionPlaces(Program program) {
         BasicBlock[] places = new BasicBlock[program.variableCount()];
         DefinitionExtractor defExtractor = new DefinitionExtractor();