diff --git a/R/parse_compat.R b/R/parse_compat.R
index 13a8665..96dd257 100644
--- a/R/parse_compat.R
+++ b/R/parse_compat.R
@@ -250,7 +250,7 @@ parse_compat_fix_output_self <- function(expr, call) {
     rlang::is_call(expr$value[[2]], "output") &&
     !isTRUE(expr$value[[3]])
   if (is_output_expr) {
-    lhs <- expr$value[[2]]
+    lhs <- expr$value[[2]][[2]]
     rhs <- expr$value[[3]]
     rewrite <-
       (is.symbol(lhs) &&
@@ -261,10 +261,10 @@ parse_compat_fix_output_self <- function(expr, call) {
        identical(lhs[[2]], rhs[[2]]))
     if (rewrite) {
       original <- expr$value
-      if (is_call(lhs, "[[")) {
-        expr$value[[2]] <- expr$value[[2]][[2]]
-      }
       expr$value[[3]] <- TRUE
+      if (rlang::is_call(lhs, "[")) {
+        expr$value[[2]][[2]] <- lhs[[2]]
+      }
       expr <- parse_add_compat(expr, "output_self", original)
     }
   }
diff --git a/R/parse_system.R b/R/parse_system.R
index 42def68..9a007bb 100644
--- a/R/parse_system.R
+++ b/R/parse_system.R
@@ -141,6 +141,7 @@ parse_system_overall <- function(exprs, call) {
 
     is_output_flag <- vlapply(exprs[is_output], function(x) isTRUE(x$rhs$expr))
     is_output_expr <- !is_output_flag
+    nms <- lapply(exprs[is_output], function(x) x$lhs$name)
 
     ## Rewrite expressions in output(x) <- expr style to just drop the
     ## special output bit now, and treat them as normal expressions.
@@ -644,7 +645,8 @@ parse_system_arrays <- function(exprs, call) {
     err <- vlapply(exprs[i], function(x) {
       is.null(x$lhs$array) &&
         !identical(x$special, "parameter") &&
-        !identical(x$special, "delay")
+        !identical(x$special, "delay") &&
+        !(identical(x$special, "output") && isTRUE(x$rhs$expr))
     })
     if (any(err)) {
       src <- lapply(exprs[i][err], "[[", "src")
diff --git a/tests/testthat/test-generate.R b/tests/testthat/test-generate.R
index dbae64a..4c935af 100644
--- a/tests/testthat/test-generate.R
+++ b/tests/testthat/test-generate.R
@@ -2805,3 +2805,23 @@ test_that("output <- TRUE version generates same code", {
 
   expect_equal(generate_dust_system(dat2), generate_dust_system(dat1))
 })
+
+
+test_that("cope with array output", {
+  dat1 <- odin_parse({
+    initial(x[]) <- 0
+    deriv(x[]) <- x[i]
+    a[] <- x[i] + 1
+    output(a) <- TRUE
+    dim(x, a) <- 5
+  })
+
+  dat2 <- odin_parse({
+    initial(x[]) <- 0
+    deriv(x[]) <- x[i]
+    output(a[]) <- x[i] + 1
+    dim(x, a) <- 5
+  })
+
+  expect_equal(generate_dust_system(dat2), generate_dust_system(dat1))
+})
diff --git a/tests/testthat/test-parse-compat.R b/tests/testthat/test-parse-compat.R
index 6c91c2a..573af51 100644
--- a/tests/testthat/test-parse-compat.R
+++ b/tests/testthat/test-parse-compat.R
@@ -294,3 +294,30 @@ test_that("disallow parsing interpolation to slice", {
                "Drop arrays from lhs of assignments from 'interpolate()'",
                fixed = TRUE)
 })
+
+
+test_that("warn about old-style output assignments", {
+  w <- expect_warning(
+    odin_parse({
+      initial(x) <- 0
+      deriv(x) <- 1
+      a <- x + 1
+      output(a) <- a
+    }),
+    "Use `TRUE` on rhs for 'output(x) <- x' expressions",
+    fixed = TRUE)
+})
+
+
+test_that("warn about old-style output assignments in arrays", {
+  w <- expect_warning(
+    odin_parse({
+      initial(x) <- 0
+      deriv(x) <- 1
+      a[] <- x + 1
+      output(a[]) <- a[i]
+      dim(a) <- 1
+    }),
+    "Use `TRUE` on rhs for 'output(x) <- x' expressions",
+    fixed = TRUE)
+})