diff --git a/src/dk/camelot64/kickc/Compiler.java b/src/dk/camelot64/kickc/Compiler.java
index d2110243c..31dca207c 100644
--- a/src/dk/camelot64/kickc/Compiler.java
+++ b/src/dk/camelot64/kickc/Compiler.java
@@ -112,6 +112,7 @@ public class Compiler {
       Pass3IdentifyAliveRanges pass3IdentifyAliveRanges = new Pass3IdentifyAliveRanges(program, log);
       pass3IdentifyAliveRanges.findLiveRanges();
 
+
       log.append("CONTROL FLOW GRAPH - LIVE RANGES");
       log.append(program.getGraph().toString(program.getScope()));
       pass2AssertSSA(program, log);
diff --git a/src/dk/camelot64/kickc/passes/Pass2AssertBlocks.java b/src/dk/camelot64/kickc/passes/Pass2AssertBlocks.java
index 55a57dbb7..c7a3ce414 100644
--- a/src/dk/camelot64/kickc/passes/Pass2AssertBlocks.java
+++ b/src/dk/camelot64/kickc/passes/Pass2AssertBlocks.java
@@ -2,6 +2,8 @@ package dk.camelot64.kickc.passes;
 
 import dk.camelot64.kickc.icl.*;
 
+import java.util.*;
+
 /** Assert that all referenced blocks exist in the program */
 public class Pass2AssertBlocks extends Pass2SsaAssertion {
 
@@ -11,16 +13,32 @@ public class Pass2AssertBlocks extends Pass2SsaAssertion {
 
    @Override
    public void check() throws AssertionFailed {
-      ControlFlowGraphBaseVisitor<Void> blockReferenceFinder = new BlockReferenceChecker(getGraph());
+      BlockReferenceChecker blockReferenceFinder = new BlockReferenceChecker(getGraph());
       blockReferenceFinder.visitGraph(getGraph());
+
+      Set<LabelRef> seenBlocks = blockReferenceFinder.getSeenBlocks();
+      Collection<ControlFlowBlock> allBlocks = getGraph().getAllBlocks();
+      for (LabelRef seenBlock : seenBlocks) {
+         ControlFlowBlock block = getGraph().getBlock(seenBlock);
+         if(!allBlocks.contains(block)) {
+            throw new AssertionFailed("Compilation Process Error! A block in the program is not contained in the allBocks list (probably a block sequence problem). " + seenBlock);
+         }
+      }
    }
 
    private static class BlockReferenceChecker extends ControlFlowGraphBaseVisitor<Void> {
 
       private ControlFlowGraph graph;
 
+      Set<LabelRef> seenBlocks;
+
       public BlockReferenceChecker(ControlFlowGraph graph) {
          this.graph = graph;
+         this.seenBlocks = new HashSet<>();
+      }
+
+      public Set<LabelRef> getSeenBlocks() {
+         return seenBlocks;
       }
 
       private void assertBlock(LabelRef blockLabel) throws AssertionFailed {
@@ -30,6 +48,7 @@ public class Pass2AssertBlocks extends Pass2SsaAssertion {
          if (blockLabel.getFullName().equals("@RETURN")) {
             return;
          }
+         seenBlocks.add(blockLabel);
          ControlFlowBlock block = graph.getBlock(blockLabel);
          if (block == null) {
             throw new AssertionFailed("Compilation Process Error! Block referenced, but not found in program. " + blockLabel);