diff --git a/src/main/java/dk/camelot64/kickc/Compiler.java b/src/main/java/dk/camelot64/kickc/Compiler.java
index c44b5d5b0..13901b4c8 100644
--- a/src/main/java/dk/camelot64/kickc/Compiler.java
+++ b/src/main/java/dk/camelot64/kickc/Compiler.java
@@ -121,6 +121,7 @@ public class Compiler {
       new Pass1AssertNoLValueIntermediate(program).execute();
       new Pass1AddTypePromotions(program).execute();
       new Pass1AssertNoRecursion(program).execute();
+      new Pass1AssertInterrupts(program).execute();
 
       getLog().append("INITIAL CONTROL FLOW GRAPH");
       getLog().append(program.getGraph().toString(program));
diff --git a/src/main/java/dk/camelot64/kickc/model/symbols/Procedure.java b/src/main/java/dk/camelot64/kickc/model/symbols/Procedure.java
index f87374478..7acf16c25 100644
--- a/src/main/java/dk/camelot64/kickc/model/symbols/Procedure.java
+++ b/src/main/java/dk/camelot64/kickc/model/symbols/Procedure.java
@@ -16,11 +16,13 @@ public class Procedure extends Scope {
    private final SymbolType returnType;
    private List<String> parameterNames;
    private boolean declaredInline;
+   private boolean declaredInterrupt;
 
    public Procedure(String name, SymbolType returnType, Scope parentScope) {
       super(name, parentScope);
       this.returnType = returnType;
       this.declaredInline = false;
+      this.declaredInterrupt = false;
    }
 
    public List<String> getParameterNames() {
@@ -73,6 +75,18 @@ public class Procedure extends Scope {
       return declaredInline;
    }
 
+   public void setDeclaredInline(boolean declaredInline) {
+      this.declaredInline = declaredInline;
+   }
+
+   public boolean isDeclaredInterrupt() {
+      return declaredInterrupt;
+   }
+
+   public void setDeclaredInterrupt(boolean declaredInterrupt) {
+      this.declaredInterrupt = declaredInterrupt;
+   }
+
    @Override
    public String toString() {
       return toString(null);
@@ -84,6 +98,9 @@ public class Procedure extends Scope {
       if(declaredInline) {
          res.append("inline ");
       }
+      if(declaredInterrupt) {
+         res.append("interrupt ");
+      }
       res.append("(" + getType().getTypeName() + ") ");
       res.append(getFullName());
       res.append("(");
@@ -123,8 +140,4 @@ public class Procedure extends Scope {
       return result;
    }
 
-   public void setDeclaredInline(boolean declaredInline) {
-      this.declaredInline = declaredInline;
-   }
-
 }
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
index e221d9bdd..49a8fb623 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
@@ -348,6 +348,8 @@ public class Pass0GenerateStatementSequence extends KickCBaseVisitor<Object> {
          StatementSource source = new StatementSource(directivesCtx.get(0));
          if(directive instanceof DirectiveInline) {
             procedure.setDeclaredInline(true);
+         } else if(directive instanceof DirectiveInterrupt) {
+            procedure.setDeclaredInterrupt(true);
          } else {
             throw new CompileError("Unsupported function directive " + directive, source);
          }
@@ -364,6 +366,11 @@ public class Pass0GenerateStatementSequence extends KickCBaseVisitor<Object> {
       return new DirectiveInline();
    }
 
+   @Override
+   public Object visitDirectiveInterrupt(KickCParser.DirectiveInterruptContext ctx) {
+      return new DirectiveInterrupt();
+   }
+
    @Override
    public Directive visitDirectiveAlign(KickCParser.DirectiveAlignContext ctx) {
       Number alignment = NumberParser.parseLiteral(ctx.NUMBER().getText());
@@ -831,6 +838,10 @@ public class Pass0GenerateStatementSequence extends KickCBaseVisitor<Object> {
    private static class DirectiveInline implements Directive {
    }
 
+   /** Function declared interrupt. */
+   private static class DirectiveInterrupt implements Directive {
+   }
+
    /** Variable memory alignment. */
    private static class DirectiveAlign implements Directive {
       private int alignment;
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass1AssertInterrupts.java b/src/main/java/dk/camelot64/kickc/passes/Pass1AssertInterrupts.java
new file mode 100644
index 000000000..cf03db580
--- /dev/null
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass1AssertInterrupts.java
@@ -0,0 +1,40 @@
+package dk.camelot64.kickc.passes;
+
+import dk.camelot64.kickc.model.CompileError;
+import dk.camelot64.kickc.model.ControlFlowBlock;
+import dk.camelot64.kickc.model.Program;
+import dk.camelot64.kickc.model.statements.Statement;
+import dk.camelot64.kickc.model.statements.StatementCall;
+import dk.camelot64.kickc.model.symbols.Procedure;
+import dk.camelot64.kickc.model.values.ProcedureRef;
+
+/** Asserts that interrupts are never called and are not declared inline */
+public class Pass1AssertInterrupts extends Pass1Base {
+
+   public Pass1AssertInterrupts(Program program) {
+      super(program);
+   }
+
+   @Override
+   public boolean step() {
+      for(ControlFlowBlock block : getGraph().getAllBlocks()) {
+         for(Statement statement : block.getStatements()) {
+            if(statement instanceof StatementCall) {
+               ProcedureRef procedureRef = ((StatementCall) statement).getProcedure();
+               Procedure procedure = getScope().getProcedure(procedureRef);
+               if(procedure.isDeclaredInterrupt()) {
+                  throw new CompileError("Error! Interrupts cannot be called.", statement.getSource());
+               }
+            }
+         }
+         for(Procedure procedure : getScope().getAllProcedures(true)) {
+            if(procedure.isDeclaredInline() && procedure.isDeclaredInterrupt()) {
+               throw new CompileError("Error! Interrupts cannot be inlined. " + procedure.toString());
+            }
+         }
+      }
+      return false;
+   }
+
+
+}
diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass1ProcedureInline.java b/src/main/java/dk/camelot64/kickc/passes/Pass1ProcedureInline.java
index b02729ad7..8e4f9df28 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass1ProcedureInline.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass1ProcedureInline.java
@@ -37,6 +37,9 @@ public class Pass1ProcedureInline extends Pass1Base {
                ProcedureRef procedureRef = call.getProcedure();
                Procedure procedure = getScope().getProcedure(procedureRef);
                if(procedure.isDeclaredInline()) {
+                  if(procedure.isDeclaredInterrupt()) {
+                     throw new CompileError("Error! Interrupts cannot be inlined. "+procedure.getRef().toString());
+                  }
                   Scope callScope = getScope().getScope(block.getScope());
                   // Remove call
                   statementsIt.remove();
diff --git a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
index 5d3d6e194..7b7656e8b 100644
--- a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
+++ b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
@@ -881,6 +881,15 @@ public class TestPrograms {
       assertError("no-mod-runtime", "Runtime modulo not supported");
    }
 
+   @Test
+   public void testNoInlineInterrupt() throws IOException, URISyntaxException {
+      assertError("no-inlineinterrupt", "Interrupts cannot be inlined");
+   }
+
+   @Test
+   public void testNoCalledInterrupt() throws IOException, URISyntaxException {
+      assertError("no-calledinterrupt", "Interrupts cannot be called.");
+   }
 
    private void assertError(String kcFile, String expectError) throws IOException, URISyntaxException {
       try {
diff --git a/src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc b/src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc
index 73da5d3dc..b63580f5f 100644
--- a/src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc
+++ b/src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc
@@ -1,4 +1,4 @@
-// A flexible sprite multiplexer routine for 24 sprites.
+// A flexible sprite multiplexer routine for 32 sprites.
 // Usage:
 // - Once:
 // - plexInit(screen): Initialize the data structures and set the screen address
@@ -9,8 +9,8 @@
 // - plexFreeNextYpos() Returns the Y-position where the next sprite is available to be shown (ie. the next pos where the next sprite is no longer in use showing something else).
 // - plexShowNextYpos() Returns the Y-position of the next sprite to show.
 //
-// In practice a good method is to wait until the raster is beyond plexFreeNextYpos() and then call plexShowSprite(). Repeat until all 24 sprites have been shown.
-// TODO: Let the caller specify the number of sprites (PLEX_COUNT)
+// In practice a good method is to wait until the raster is beyond plexFreeNextYpos() and then call plexShowSprite(). Repeat until all 32 sprites have been shown.
+// TODO: Let the caller specify the number of sprites to use (or add PLEX_ENABLE[PLEX_COUNT])
 
 import "c64"
 
diff --git a/src/test/java/dk/camelot64/kickc/test/kc/no-calledinterrupt.kc b/src/test/java/dk/camelot64/kickc/test/kc/no-calledinterrupt.kc
new file mode 100644
index 000000000..6204ed70d
--- /dev/null
+++ b/src/test/java/dk/camelot64/kickc/test/kc/no-calledinterrupt.kc
@@ -0,0 +1,12 @@
+// Test that inline interrupts not allowed
+
+byte* SCREEN = $400;
+
+void main() {
+    SCREEN[0]++;
+    irq();
+}
+
+interrupt void irq() {
+    SCREEN[1]++;
+}
\ No newline at end of file
diff --git a/src/test/java/dk/camelot64/kickc/test/kc/no-inlineinterrupt.kc b/src/test/java/dk/camelot64/kickc/test/kc/no-inlineinterrupt.kc
new file mode 100644
index 000000000..1cfef84bc
--- /dev/null
+++ b/src/test/java/dk/camelot64/kickc/test/kc/no-inlineinterrupt.kc
@@ -0,0 +1,11 @@
+// Test that inline interrupts not allowed
+
+byte* SCREEN = $400;
+
+void main() {
+    SCREEN[0]++;
+}
+
+inline interrupt void irq() {
+    SCREEN[1]++;
+}
\ No newline at end of file
diff --git a/src/test/java/dk/camelot64/kickc/test/kc/simple-multiplexer.kc b/src/test/java/dk/camelot64/kickc/test/kc/simple-multiplexer.kc
index 635a6fcc4..4ef2ce299 100644
--- a/src/test/java/dk/camelot64/kickc/test/kc/simple-multiplexer.kc
+++ b/src/test/java/dk/camelot64/kickc/test/kc/simple-multiplexer.kc
@@ -3,8 +3,8 @@ import "c64"
 import "multiplexer"
 
 // Location of screen & sprites
-byte* SPRITE = $2000;
 byte* SCREEN = $400;
+byte* SPRITE = $2000;
 byte* YSIN = $2100;
 
 kickasm(pc YSIN) {{
diff --git a/src/test/java/dk/camelot64/kickc/test/ref/simple-multiplexer.log b/src/test/java/dk/camelot64/kickc/test/ref/simple-multiplexer.log
index e94ed7781..e6cd65cd3 100644
--- a/src/test/java/dk/camelot64/kickc/test/ref/simple-multiplexer.log
+++ b/src/test/java/dk/camelot64/kickc/test/ref/simple-multiplexer.log
@@ -194,7 +194,7 @@ inline void vicSelectGfxBank(byte* gfx) {
 
 Importing multiplexer
 PARSING src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc
-// A flexible sprite multiplexer routine for 24 sprites.
+// A flexible sprite multiplexer routine for 32 sprites.
 // Usage:
 // - Once:
 // - plexInit(screen): Initialize the data structures and set the screen address
@@ -205,8 +205,8 @@ PARSING src/test/java/dk/camelot64/kickc/test/kc/multiplexer.kc
 // - plexFreeNextYpos() Returns the Y-position where the next sprite is available to be shown (ie. the next pos where the next sprite is no longer in use showing something else).
 // - plexShowNextYpos() Returns the Y-position of the next sprite to show.
 //
-// In practice a good method is to wait until the raster is beyond plexFreeNextYpos() and then call plexShowSprite(). Repeat until all 24 sprites have been shown.
-// TODO: Let the caller specify the number of sprites (PLEX_COUNT)
+// In practice a good method is to wait until the raster is beyond plexFreeNextYpos() and then call plexShowSprite(). Repeat until all 32 sprites have been shown.
+// TODO: Let the caller specify the number of sprites to use (or add PLEX_ENABLE[PLEX_COUNT])
 
 import "c64"