diff --git a/src/apple2.text.c b/src/apple2.text.c
index 960bdbd..6ca1788 100644
--- a/src/apple2.text.c
+++ b/src/apple2.text.c
@@ -320,7 +320,13 @@ apple2_text_area(vm_area *area, vm_bitfont *font, size_t addr)
     // (0x0800-0x0BFF) respectively. If the given address is not in
     // those (contiguous) ranges, then let's bail.
     if (addr < 0x0400 || addr > 0x0BFF) {
-        return 0;
+        return ERR_INVALID;
+    }
+
+    // Certain addresses are not meant to be displayable, and are
+    // actually used for system data
+    if (buffer_rows[addr] == -1 || buffer_cols[addr] == -1) {
+        return ERR_INVALID;
     }
 
     // In a given page for 40-column mode, you get 960 grid parts that
diff --git a/tests/apple2.text.c b/tests/apple2.text.c
index 127c0d0..74d23da 100644
--- a/tests/apple2.text.c
+++ b/tests/apple2.text.c
@@ -39,7 +39,7 @@ Test(apple2_text, area)
     vm_area area;
 
     cr_assert_neq(apple2_text_area(&area, font, 0x0301), OK);
-    cr_assert_neq(apple2_text_area(&area, font, 0x0461), OK);
+    cr_assert_neq(apple2_text_area(&area, font, 0x04FB), OK);
     cr_assert_eq(apple2_text_area(&area, font, 0x0537), OK);
 
     // FIXME: need a proper test for area; we're missing one because the