diff --git a/src/builtins/set.rs b/src/builtins/set.rs
index 54574e19c..c96f6f32b 100644
--- a/src/builtins/set.rs
+++ b/src/builtins/set.rs
@@ -937,6 +937,17 @@ fn set_internal(
 
     // Setting with explicit indexes like `set foo[3] ...` has additional error handling.
     if !split.indexes.is_empty() {
+        // Indexes must be > 0. (Note split_var_and_indexes negates negative values).
+        for ind in &split.indexes {
+            if *ind <= 0 {
+                streams.err.append(wgettext_fmt!(
+                    "%ls: array index out of bounds\n",
+                    cmd
+                ));
+                builtin_print_error_trailer(parser, streams.err, cmd);
+                return STATUS_INVALID_ARGS;
+            }
+        }
         // Append and prepend are disallowed.
         if opts.append || opts.prepend {
             streams.err.append(wgettext_fmt!(
diff --git a/tests/checks/set.fish b/tests/checks/set.fish
index 20e2f68a8..68d4ab9e9 100644
--- a/tests/checks/set.fish
+++ b/tests/checks/set.fish
@@ -1001,4 +1001,16 @@ env -u XDG_CONFIG_HOME HOME=$PWD/empty LC_ALL=en_US.UTF-8 $FISH -c 'set -S LC_AL
 # CHECK: $LC_ALL[1]: |en_US.UTF-8|
 # CHECK: $LC_ALL: originally inherited as |en_US.UTF-8|
 
+# This used to crash
+set line[0] ""
+# CHECKERR: set: array index out of bounds
+# CHECKERR: {{.*}}set.fish (line {{\d+}}):
+# CHECKERR: set line[0] ""
+# CHECKERR: ^
+# CHECKERR: (Type 'help set' for related documentation)
+
+
+echo Still here
+# CHECK: Still here
+
 exit 0