diff --git a/src/main/java/dk/camelot64/kickc/Compiler.java b/src/main/java/dk/camelot64/kickc/Compiler.java
index 23310454f..cb8d88400 100644
--- a/src/main/java/dk/camelot64/kickc/Compiler.java
+++ b/src/main/java/dk/camelot64/kickc/Compiler.java
@@ -222,7 +222,7 @@ public class Compiler {
       assertions.add(new Pass2AssertNoLabels(program));
       assertions.add(new Pass2AssertSingleAssignment(program));
       assertions.add(new Pass2AssertRValues(program));
-      //assertions.add(new Pass2AssertPhiPredecessors(program));
+      assertions.add(new Pass2AssertPhiPredecessors(program));
       for(Pass2SsaAssertion assertion : assertions) {
          assertion.check();
       }
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass1GenerateSingleStaticAssignmentForm.java b/src/main/java/dk/camelot64/kickc/passes/Pass1GenerateSingleStaticAssignmentForm.java
index 2d6db335d..db834cb48 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass1GenerateSingleStaticAssignmentForm.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass1GenerateSingleStaticAssignmentForm.java
@@ -197,7 +197,7 @@ public class Pass1GenerateSingleStaticAssignmentForm extends Pass1Base {
                      VariableRef phiLValVarRef = phiVariable.getVariable();
                      VariableVersion versioned = (VariableVersion) getScope().getVariable(phiLValVarRef);
                      VariableUnversioned unversioned = versioned.getVersionOf();
-                     List<ControlFlowBlock> predecessors = getPredecessors(block);
+                     List<ControlFlowBlock> predecessors = getPhiPredecessors(block, getProgram());
                      for(ControlFlowBlock predecessor : predecessors) {
                         LabelRef predecessorLabel = predecessor.getLabel();
                         Map<VariableUnversioned, VariableVersion> predecessorMap = symbolMap.get(predecessorLabel);
@@ -245,15 +245,15 @@ public class Pass1GenerateSingleStaticAssignmentForm extends Pass1Base {
     * @param block The block to examine
     * @return All predecessor blocks
     */
-   private List<ControlFlowBlock> getPredecessors(ControlFlowBlock block) {
-      List<ControlFlowBlock> predecessors = getGraph().getPredecessors(block);
-      Symbol symbol = getScope().getSymbol(block.getLabel());
+   public static List<ControlFlowBlock> getPhiPredecessors(ControlFlowBlock block, Program program) {
+      List<ControlFlowBlock> predecessors = program.getGraph().getPredecessors(block);
+      Symbol symbol = program.getScope().getSymbol(block.getLabel());
       if(symbol instanceof Procedure) {
          Procedure procedure = (Procedure) symbol;
-         if(procedure.getInterruptType()!=null || Pass2ConstantIdentification.isAddressOfUsed(procedure.getRef(), getProgram())) {
+         if(procedure.getInterruptType()!=null || Pass2ConstantIdentification.isAddressOfUsed(procedure.getRef(), program)) {
             // Find all root-level predecessors to the main block
-            ControlFlowBlock mainBlock = getGraph().getBlock(new LabelRef(SymbolRef.MAIN_PROC_NAME));
-            List<ControlFlowBlock> mainPredecessors = getGraph().getPredecessors(mainBlock);
+            ControlFlowBlock mainBlock = program.getGraph().getBlock(new LabelRef(SymbolRef.MAIN_PROC_NAME));
+            List<ControlFlowBlock> mainPredecessors = program.getGraph().getPredecessors(mainBlock);
             for(ControlFlowBlock mainPredecessor : mainPredecessors) {
                if(mainPredecessor.getScope().equals(ScopeRef.ROOT)) {
                   predecessors.add(mainPredecessor);
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass2AssertPhiPredecessors.java b/src/main/java/dk/camelot64/kickc/passes/Pass2AssertPhiPredecessors.java
index 781346e6b..e1065d84b 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass2AssertPhiPredecessors.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass2AssertPhiPredecessors.java
@@ -21,8 +21,9 @@ public class Pass2AssertPhiPredecessors extends Pass2SsaAssertion {
       for(ControlFlowBlock block : getGraph().getAllBlocks()) {
          if(block.hasPhiBlock()) {
             StatementPhiBlock phiBlock = block.getPhiBlock();
+            List<ControlFlowBlock> phiPredecessors = Pass1GenerateSingleStaticAssignmentForm.getPhiPredecessors(block, getProgram());
             List<LabelRef> predecessors =
-                  getGraph().getPredecessors(block).stream().map(ControlFlowBlock::getLabel).collect(Collectors.toList());
+                  phiPredecessors.stream().map(ControlFlowBlock::getLabel).collect(Collectors.toList());
             for(StatementPhiBlock.PhiVariable phiVariable : phiBlock.getPhiVariables()) {
                for(StatementPhiBlock.PhiRValue phiRValue : phiVariable.getValues()) {
                   if(!predecessors.contains(phiRValue.getPredecessor())) {