diff --git a/src/asm/matcher/mod.rs b/src/asm/matcher/mod.rs
index 747d610a..8db4cab8 100644
--- a/src/asm/matcher/mod.rs
+++ b/src/asm/matcher/mod.rs
@@ -586,7 +586,8 @@ fn match_with_rule<'src>(
 
             asm::RulePatternPart::Whitespace =>
             {
-                if walker.next_token().kind != syntax::TokenKind::Whitespace
+                if !walker.is_over() &&
+                    walker.next_token().kind != syntax::TokenKind::Whitespace
                 {
                     return vec![];
                 }
diff --git a/tests/issue216/ok.asm b/tests/issue216/ok.asm
new file mode 100644
index 00000000..7587a38e
--- /dev/null
+++ b/tests/issue216/ok.asm
@@ -0,0 +1,16 @@
+#subruledef acc {
+    a => 0xaa
+    b => 0xbb
+}
+
+#subruledef paropts {
+    {} => 0x00
+    FOO => 0x01
+}
+
+#ruledef {
+    abs {reg: acc} {p: paropts} => 0xee @ reg @ p
+}
+
+abs a FOO ; = 0xeeaa01
+abs a ; = 0xeeaa00
\ No newline at end of file