diff --git a/asllib/Parser0.mly b/asllib/Parser0.mly
index a9dd3140c..031b02770 100644
--- a/asllib/Parser0.mly
+++ b/asllib/Parser0.mly
@@ -348,7 +348,7 @@ let binop_expr(e, b) ==
       | ~=e; DOT; ~=bracketed(clist(ident));          < AST.E_GetFields >
       | ~=e; ~=bracketed(clist(slice));               < AST.E_Slice     >
       | ~=bracketed(clist(expr));                     < AST.E_Concat    >
-      | ~=e; IN; ~=pattern;                           < AST.E_Pattern   >
+      | ~=e; IN; ~=bpattern;                           < AST.E_Pattern   >
       | ~=annotated(ty_non_tuple); UNKNOWN;           < AST.E_Unknown   >
       (*
       | ~=e; LT; ~=clist(slice); GT;          < AST.E_Slice     >
@@ -645,6 +645,7 @@ let otherwise == annotated (OTHERWISE; possibly_empty_block)
 
 let pattern_list == ~=nclist(pattern); < AST.Pattern_Any >
 let pattern ==
+    | bpattern
     | MINUS; { AST.Pattern_All }
     | ~=MASK_LIT; < AST.Pattern_Mask >
 
@@ -653,8 +654,7 @@ let pattern ==
       | ~=qualident; < AST.E_Var >
     ); < AST.Pattern_Single >
 
-    | braced(apattern_list)
-
+let bpattern == braced(apattern_list)
 let apattern_list == ~=nclist(apattern); < AST.Pattern_Any >
 let apattern ==
   | ~=expr; < AST.Pattern_Single >
diff --git a/asllib/tests/regressions.t/asl0-patterns.asl b/asllib/tests/regressions.t/asl0-patterns.asl
new file mode 100644
index 000000000..9d34a388b
--- /dev/null
+++ b/asllib/tests/regressions.t/asl0-patterns.asl
@@ -0,0 +1,6 @@
+integer main()
+    bits(64) x = Zeros(64);
+    y = x[1+:10]; // this would be invalid ASL0, but we use it in the XML
+    if x[0+:4] IN '10x1' then
+        z = 1;
+    return 1;
diff --git a/asllib/tests/regressions.t/run.t b/asllib/tests/regressions.t/run.t
index ba0d65514..c8f2256c1 100644
--- a/asllib/tests/regressions.t/run.t
+++ b/asllib/tests/regressions.t/run.t
@@ -301,6 +301,10 @@ Required tests:
   $ aslref array-with-enums.asl
   $ aslref array.asl
   $ aslref -0 assign-v0.asl
+  $ aslref -0 asl0-patterns.asl
+  File asl0-patterns.asl, line 4, characters 25 to 29:
+  ASL Error: Cannot parse.
+  [1]
   $ aslref assign1.asl
   $ aslref big-ints.asl
   $ aslref bitfields.asl