diff --git a/src/main/java/dk/camelot64/kickc/fragment/AsmFragmentTemplateSynthesisRule.java b/src/main/java/dk/camelot64/kickc/fragment/AsmFragmentTemplateSynthesisRule.java
index ffc336a12..fd7285136 100644
--- a/src/main/java/dk/camelot64/kickc/fragment/AsmFragmentTemplateSynthesisRule.java
+++ b/src/main/java/dk/camelot64/kickc/fragment/AsmFragmentTemplateSynthesisRule.java
@@ -479,17 +479,17 @@ class AsmFragmentTemplateSynthesisRule {
       synths.add(new AsmFragmentTemplateSynthesisRule("(.*)vw(.)c1(.*)", null, null , "$1vd$2c1$3", null, null));
       synths.add(new AsmFragmentTemplateSynthesisRule("(.*)vw(.)c2(.*)", null, null , "$1vd$2c2$3", null, null));
 
-      /* Removed pending optimization!
+      /* Removed awaiting optimization
       // Rewrite constant unsigned word values to constant signed dword values
       synths.add(new AsmFragmentTemplateSynthesisRule("(.*)vwuc1(.*)", null, null , "$1vdsc1$2", null, null));
       synths.add(new AsmFragmentTemplateSynthesisRule("(.*)vwuc2(.*)", null, null , "$1vdsc2$2", null, null));
       */
 
-      /*
+      /* Removed awaiting optimization
       // Rewrite any zeropage pointer as an unsigned word zeropage values
-      synths.add(new AsmFragmentTemplateSynthesisRule("(.*)p..z(.)(.*)", null, null , "$1vwuz$2$3", null, null));
+      synths.add(new AsmFragmentTemplateSynthesisRule("(.*)p..z(.)(.*)", ".*p..z._deref.*", null , "$1vwuz$2$3", null, null));
       // Rewrite any constant pointer as an constant unsigned word
-      synths.add(new AsmFragmentTemplateSynthesisRule("(.*)p..c(.)(.*)", null, null , "$1vwuc$2$3", null, null));
+      synths.add(new AsmFragmentTemplateSynthesisRule("(.*)p..c(.)(.*)", ".*p..z._deref.*", null , "$1vwuc$2$3", null, null));
       */
 
       // Synthesize some constant pointers as constant words (remove when the above section can be included)
diff --git a/src/main/java/dk/camelot64/kickc/model/statements/StatementSource.java b/src/main/java/dk/camelot64/kickc/model/statements/StatementSource.java
index c4fd04b6e..63df1d555 100644
--- a/src/main/java/dk/camelot64/kickc/model/statements/StatementSource.java
+++ b/src/main/java/dk/camelot64/kickc/model/statements/StatementSource.java
@@ -2,6 +2,7 @@ package dk.camelot64.kickc.model.statements;
 
 import org.antlr.v4.runtime.CharStream;
 import org.antlr.v4.runtime.ParserRuleContext;
+import org.antlr.v4.runtime.Token;
 import org.antlr.v4.runtime.misc.Interval;
 
 /** Contains information about the source of a program statement */
@@ -15,9 +16,13 @@ public class StatementSource {
 
    @Override
    public String toString() {
-      CharStream stream = context.getStart().getInputStream();
-      Interval interval = new Interval(context.getStart().getStartIndex(), context.getStop().getStopIndex());
-      String sourceMessage = "File "+stream.getSourceName()+"\nLine "+context.getStart().getLine()+ "\n" +stream.getText(interval);
-      return sourceMessage;
+      Token contextStart = context.getStart();
+      if(contextStart != null) {
+         CharStream stream = contextStart.getInputStream();
+         Interval interval = new Interval(contextStart.getStartIndex(), context.getStop().getStopIndex());
+         return "File " + stream.getSourceName() + "\nLine " + contextStart.getLine() + "\n" + stream.getText(interval);
+      } else {
+         return "";
+      }
    }
 }
diff --git a/src/main/java/dk/camelot64/kickc/model/symbols/Scope.java b/src/main/java/dk/camelot64/kickc/model/symbols/Scope.java
index 268d42561..a9fb835fe 100644
--- a/src/main/java/dk/camelot64/kickc/model/symbols/Scope.java
+++ b/src/main/java/dk/camelot64/kickc/model/symbols/Scope.java
@@ -1,5 +1,6 @@
 package dk.camelot64.kickc.model.symbols;
 
+import dk.camelot64.kickc.model.CompileError;
 import dk.camelot64.kickc.model.Program;
 import dk.camelot64.kickc.model.Registers;
 import dk.camelot64.kickc.model.VariableRegisterWeights;
@@ -97,7 +98,7 @@ public abstract class Scope implements Symbol {
 
    public Symbol add(Symbol symbol) {
       if(symbols.get(symbol.getLocalName()) != null) {
-         throw new RuntimeException("Symbol already declared " + symbol.getLocalName());
+         throw new CompileError("Symbol already declared " + symbol.getLocalName());
       }
       symbols.put(symbol.getLocalName(), symbol);
       return symbol;
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
index b46f5161e..86a833bc1 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
@@ -299,7 +299,12 @@ public class Pass0GenerateStatementSequence extends KickCBaseVisitor<Object> {
    public Object visitDeclVariable(KickCParser.DeclVariableContext ctx) {
       SymbolType type = (SymbolType) visit(ctx.typeDecl());
       String varName = ctx.NAME().getText();
-      VariableUnversioned lValue = getCurrentSymbols().addVariable(varName, type);
+      VariableUnversioned lValue;
+      try {
+         lValue = getCurrentSymbols().addVariable(varName, type);
+      } catch(CompileError e) {
+         throw new CompileError(e.getMessage(), new StatementSource(ctx));
+      }
       // Add directives
       addDirectives(type, lValue, ctx.directive());
       // Array / String variables are implicitly constant
@@ -669,7 +674,11 @@ public class Pass0GenerateStatementSequence extends KickCBaseVisitor<Object> {
       Variable lValue;
       if(forDeclCtx.typeDecl() != null) {
          SymbolType type = (SymbolType) visit(forDeclCtx.typeDecl());
-         lValue = getCurrentSymbols().addVariable(varName, type);
+         try {
+            lValue = getCurrentSymbols().addVariable(varName, type);
+         } catch(CompileError e) {
+            throw new CompileError(e.getMessage(), new StatementSource(forDeclCtx));
+         }
          // Add directives
          addDirectives(type, lValue, forDeclCtx.directive());
       } else {
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass2ConstantIdentification.java b/src/main/java/dk/camelot64/kickc/passes/Pass2ConstantIdentification.java
index a2a360398..b2e5cbb4d 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass2ConstantIdentification.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass2ConstantIdentification.java
@@ -68,7 +68,8 @@ public class Pass2ConstantIdentification extends Pass2SsaOptimization {
                throw new CompileError(
                      "Constant variable has a non-matching type \n variable: " + variable.toString(getProgram()) +
                            "\n value: (" + valueType.toString() + ") " + constVal.calculateLiteral(getScope()) +
-                           "\n value definition: " + constVal.toString(getProgram()));
+                           "\n value definition: " + constVal.toString(getProgram())
+               );
             }
          }
 
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass4AssertNoCpuClobber.java b/src/main/java/dk/camelot64/kickc/passes/Pass4AssertNoCpuClobber.java
index 2e0353147..eda09a609 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass4AssertNoCpuClobber.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass4AssertNoCpuClobber.java
@@ -4,6 +4,7 @@ import dk.camelot64.kickc.asm.AsmClobber;
 import dk.camelot64.kickc.asm.AsmProgram;
 import dk.camelot64.kickc.asm.AsmSegment;
 import dk.camelot64.kickc.model.*;
+import dk.camelot64.kickc.model.statements.StatementSource;
 import dk.camelot64.kickc.model.values.RValue;
 import dk.camelot64.kickc.model.values.VariableRef;
 import dk.camelot64.kickc.model.statements.Statement;
@@ -110,16 +111,17 @@ public class Pass4AssertNoCpuClobber extends Pass2Base {
                // Alive and not assigned to - clobber not allowed!
                if(clobberRegisters.contains(aliveVarRegister)) {
                   if(verbose) {
-                     getLog().append("Error! Alive variable " + aliveVar + " register " + aliveVarRegister + " clobbered by the ASM generated by statement " + statement);
+                     throw new CompileError(
+                           "Error! Generated ASM has register clobber problem. " +
+                                 "Alive variable "+aliveVar + " register " + aliveVarRegister + " clobbered by the ASM generated by statement "+statement.toString(getProgram(), true),
+                           statement.getSource()
+                     );
                   }
                   clobberProblem = true;
                }
             }
          }
       }
-      if(verbose && clobberProblem) {
-         getLog().append(asm.toString(true));
-      }
       return clobberProblem;
    }
 
diff --git a/src/test/java/dk/camelot64/kickc/test/TestFragments.java b/src/test/java/dk/camelot64/kickc/test/TestFragments.java
index a67407a34..ee6093ee5 100644
--- a/src/test/java/dk/camelot64/kickc/test/TestFragments.java
+++ b/src/test/java/dk/camelot64/kickc/test/TestFragments.java
@@ -142,7 +142,7 @@ public class TestFragments {
    }
 
    /**
-    * Test that  a specific fragment can be succesfully loaded/synthesized
+    * Test that a specific fragment can be succesfully loaded/synthesized
     * @param signature The fragment signature
     */
    private void testFragmentExists(String signature) {
diff --git a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
index 16972bae4..d6f34240a 100644
--- a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
+++ b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
@@ -44,6 +44,11 @@ public class TestPrograms {
       AsmFragmentTemplateUsages.logUsages(log, false, false, false, false, false, false);
    }
 
+   @Test
+   public void testNoLocalScope() throws IOException, URISyntaxException {
+      assertError("nolocalscope", "Symbol already declared");
+   }
+
    @Test
    public void testTypeMix() throws IOException, URISyntaxException {
       compileAndCompare("type-mix");
@@ -288,7 +293,7 @@ public class TestPrograms {
 
    @Test
    public void testUnrollInfinite() throws IOException, URISyntaxException {
-      assertError("unroll-infinite", "Loop cannot be unrolled.");
+      assertError("unroll-infinite", "Loop cannot be unrolled.", false);
    }
 
    @Test
@@ -1143,7 +1148,7 @@ public class TestPrograms {
 
    @Test
    public void testNoReturn() throws IOException, URISyntaxException {
-      assertError("noreturn", "Method must end with a return statement");
+      assertError("noreturn", "Method must end with a return statement", false);
    }
 
    @Test
@@ -1158,7 +1163,7 @@ public class TestPrograms {
 
    @Test
    public void testInvalidConstType() throws IOException, URISyntaxException {
-      assertError("invalid-consttype", "Constant variable has a non-matching type");
+      assertError("invalid-consttype", "Constant variable has a non-matching type", false);
    }
 
    @Test
@@ -1173,12 +1178,12 @@ public class TestPrograms {
 
    @Test
    public void testArrayLengthMismatch() throws IOException, URISyntaxException {
-      assertError("array-length-mismatch", "Array length mismatch");
+      assertError("array-length-mismatch", "Array length mismatch", false);
    }
 
    @Test
    public void testStringLengthMismatch() throws IOException, URISyntaxException {
-      assertError("string-length-mismatch", "Array length mismatch");
+      assertError("string-length-mismatch", "Array length mismatch", false);
    }
 
    @Test
@@ -1188,17 +1193,17 @@ public class TestPrograms {
 
    @Test
    public void testRegisterClobber() throws IOException, URISyntaxException {
-      assertError("register-clobber", "CLOBBER ERROR");
+      assertError("register-clobber", "register clobber problem", false);
    }
 
    @Test
    public void testRecursionError() throws IOException, URISyntaxException {
-      assertError("recursion-error", "Recursion");
+      assertError("recursion-error", "Recursion", false);
    }
 
    @Test
    public void testRecursionComplexError() throws IOException, URISyntaxException {
-      assertError("recursion-error-complex", "Recursion");
+      assertError("recursion-error-complex", "Recursion", false);
    }
 
    @Test
@@ -1223,7 +1228,7 @@ public class TestPrograms {
 
    @Test
    public void testNoInlineInterrupt() throws IOException, URISyntaxException {
-      assertError("no-inlineinterrupt", "Interrupts cannot be inlined");
+      assertError("no-inlineinterrupt", "Interrupts cannot be inlined", false);
    }
 
    @Test
@@ -1233,12 +1238,12 @@ public class TestPrograms {
 
    @Test
    public void testNoParamInterrupt() throws IOException, URISyntaxException {
-      assertError("no-paraminterrupt", "Interrupts cannot have parameters.");
+      assertError("no-paraminterrupt", "Interrupts cannot have parameters.", false);
    }
 
    @Test
    public void testNoReturnInterrupt() throws IOException, URISyntaxException {
-      assertError("no-returninterrupt", "Interrupts cannot return anything.");
+      assertError("no-returninterrupt", "Interrupts cannot return anything.", false);
    }
 
    @Test
@@ -1247,12 +1252,20 @@ public class TestPrograms {
    }
 
    private void assertError(String kcFile, String expectError) throws IOException, URISyntaxException {
+      assertError(kcFile, expectError, true);
+   }
+
+   private void assertError(String kcFile, String expectError, boolean expectLineNumber) throws IOException, URISyntaxException {
       try {
          compileAndCompare(kcFile);
       } catch(CompileError e) {
          System.out.println("Got error: " + e.getMessage());
          // expecting error!
          assertTrue("Error message expected  '" + expectError + "' - was:" + e.getMessage(), e.getMessage().contains(expectError));
+         if(expectLineNumber) {
+            // expecting line number!
+            assertTrue("Error message expected  line number - was:" + e.getMessage(), e.getMessage().contains("Line"));
+         }
          return;
       }
       fail("Expected compile error.");
diff --git a/src/test/kc/nolocalscope.kc b/src/test/kc/nolocalscope.kc
new file mode 100644
index 000000000..3ba6b43eb
--- /dev/null
+++ b/src/test/kc/nolocalscope.kc
@@ -0,0 +1,10 @@
+// Illustrates problem with not introducing local scopes inside loops etc
+
+import "print"
+
+void main() {
+    for (byte i: 0..5)
+        print_ln();
+    for (byte i: 0..5)
+        print_str_ln(" xxxxx@");
+}
\ No newline at end of file