diff --git a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
index 478f479de..a81137115 100644
--- a/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
+++ b/src/main/java/dk/camelot64/kickc/passes/Pass0GenerateStatementSequence.java
@@ -2766,7 +2766,7 @@ public class Pass0GenerateStatementSequence extends KickCParserBaseVisitor<Objec
             List<PrePostModifier> modifiers,
             StatementSource source) {
          for(PrePostModifier mod : modifiers) {
-            if(mod.child instanceof ConstantRef) {
+            if(mod.child instanceof ConstantValue) {
                throw new CompileError("Constants can not be modified " + mod.child.toString(), source);
             }
             Statement stmt = new StatementAssignment((LValue) mod.child, mod.operator, copyLValue((LValue) mod.child), false, source, Comment.NO_COMMENTS);
diff --git a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
index 2d1a44b72..fd874d6ab 100644
--- a/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
+++ b/src/test/java/dk/camelot64/kickc/test/TestPrograms.java
@@ -666,6 +666,11 @@ public class TestPrograms {
       compileAndCompare("examples/conio/nacht-screen.c");
    }
 
+   @Test
+   public void testPostIncrementProblem5() throws IOException, URISyntaxException {
+      assertError("post-increment-problem-5.c", "Constants can not be modified");
+   }
+
    @Test
    public void testPostIncrementProblem4() throws IOException, URISyntaxException {
       compileAndCompare("post-increment-problem-4.c");
@@ -1447,7 +1452,7 @@ public class TestPrograms {
 
    @Test
    public void testDyppa2() throws IOException, URISyntaxException {
-      compileAndCompare("complex/dyppa2/dyppa2.c", log());
+      compileAndCompare("complex/dyppa2/dyppa2.c");
    }
 
    @Test
diff --git a/src/test/kc/complex/dyppa2/dyppa2.c b/src/test/kc/complex/dyppa2/dyppa2.c
new file mode 100644
index 000000000..3b2bbbdf6
--- /dev/null
+++ b/src/test/kc/complex/dyppa2/dyppa2.c
@@ -0,0 +1,33 @@
+// Chunky DYPP with arbitrary sinus
+// First implemented as dyppa.asm in 2011
+
+#pragma emulator("C64Debugger")
+
+#include <c64.h>
+#include <string.h>
+
+// The DYPPA charset containing the sloped offset characters
+char __address(0x2000) DYPPA_CHARSET[0x0800] = kickasm(resource "dyppacharset.bin") {{
+    .var dyppaFile = LoadBinary("dyppacharset.bin", "Charset=$000,Tables=$800")
+    .fill dyppaFile.getCharsetSize(), dyppaFile.getCharset(i) 
+}};
+
+// The DYPPA tables mapping the slopes, offsets and pixels to the right character in the charset
+// for(offset:0..7) for(slope:0..f) for(pixels: 0..f) glyph_id(offset,slope,pixels)  
+char align(0x100) DYPPA_TABLE[0x0800] = kickasm(resource "dyppacharset.bin") {{
+    .var dyppaFile2 = LoadBinary("dyppacharset.bin", "Charset=$000,Tables=$800")
+    .fill dyppaFile2.getTablesSize(), dyppaFile2.getTables(i) 
+}};
+
+void main() {
+    VICII->MEMORY = toD018(DEFAULT_SCREEN, DYPPA_CHARSET);
+    memset(DEFAULT_SCREEN, DYPPA_TABLE[0], 1000);
+
+    for(;;) {
+        (*(DEFAULT_SCREEN+999))++;
+    }
+
+}
+
+
+
diff --git a/src/test/kc/complex/dyppa2/dyppacharset.bin b/src/test/kc/complex/dyppa2/dyppacharset.bin
new file mode 100644
index 000000000..98721d73f
Binary files /dev/null and b/src/test/kc/complex/dyppa2/dyppacharset.bin differ
diff --git a/src/test/kc/post-increment-problem-5.c b/src/test/kc/post-increment-problem-5.c
new file mode 100644
index 000000000..4a5b9fed2
--- /dev/null
+++ b/src/test/kc/post-increment-problem-5.c
@@ -0,0 +1,8 @@
+// Post-increment expression causes  java.lang.ClassCastException: class dk.camelot64.kickc.model.values.ConstantBinary cannot be cast to class dk.camelot64.kickc.model.values.LValue
+// Should result in a proper error
+
+char* const SCREEN = 0x0400;
+
+void main() {
+    *(SCREEN+999)++;
+}