diff --git a/src/Command.zig b/src/Command.zig
index ce606f770..f963a1857 100644
--- a/src/Command.zig
+++ b/src/Command.zig
@@ -256,7 +256,10 @@ pub fn expandPath(alloc: Allocator, cmd: []const u8) !?[]u8 {
         const full_path = path_buf[0..path_len :0];
 
         // Stat it
-        const f = std.fs.openFileAbsolute(full_path, .{}) catch |err| switch (err) {
+        const f = std.fs.cwd().openFile(
+            full_path,
+            .{},
+        ) catch |err| switch (err) {
             error.FileNotFound => continue,
             error.AccessDenied => {
                 // Accumulate this and return it later so we can try other
diff --git a/src/apprt/surface.zig b/src/apprt/surface.zig
index c7ebc6ac8..58e3cea9b 100644
--- a/src/apprt/surface.zig
+++ b/src/apprt/surface.zig
@@ -9,7 +9,7 @@ const Config = @import("../config.zig").Config;
 pub const Message = union(enum) {
     /// Represents a write request. Magic number comes from the max size
     /// we want this union to be.
-    pub const WriteReq = termio.MessageData(u8, 256);
+    pub const WriteReq = termio.MessageData(u8, 255);
 
     /// Set the title of the surface.
     /// TODO: we should change this to a "WriteReq" style structure in
diff --git a/src/terminal/Parser.zig b/src/terminal/Parser.zig
index 154dfee22..785fd938e 100644
--- a/src/terminal/Parser.zig
+++ b/src/terminal/Parser.zig
@@ -378,7 +378,11 @@ fn doAction(self: *Parser, action: TransitionAction, c: u8) ?Action {
                 self.param_acc *|= 10;
             }
             self.param_acc +|= c - '0';
-            self.param_acc_idx += 1;
+
+            // Increment our accumulator index. If we overflow then
+            // we're out of bounds and we exit immediately.
+            self.param_acc_idx, const overflow = @addWithOverflow(self.param_acc_idx, 1);
+            if (overflow > 0) break :param null;
 
             // The client is expected to perform no action.
             break :param null;
@@ -388,6 +392,9 @@ fn doAction(self: *Parser, action: TransitionAction, c: u8) ?Action {
             break :osc_put null;
         },
         .csi_dispatch => csi_dispatch: {
+            // Ignore too many parameters
+            if (self.params_idx >= MAX_PARAMS) break :csi_dispatch null;
+
             // Finalize parameters if we have one
             if (self.param_acc_idx > 0) {
                 self.params[self.params_idx] = self.param_acc;
@@ -904,3 +911,22 @@ test "csi followed by utf8" {
         try testing.expect(a[2] == null);
     }
 }
+
+test "csi: too many params" {
+    var p = init();
+    _ = p.next(0x1B);
+    _ = p.next('[');
+    for (0..100) |_| {
+        _ = p.next('1');
+        _ = p.next(';');
+    }
+    _ = p.next('1');
+
+    {
+        const a = p.next('C');
+        try testing.expect(p.state == .ground);
+        try testing.expect(a[0] == null);
+        try testing.expect(a[1] == null);
+        try testing.expect(a[2] == null);
+    }
+}
diff --git a/src/terminal/stream.zig b/src/terminal/stream.zig
index 1fda8c514..4309db4f9 100644
--- a/src/terminal/stream.zig
+++ b/src/terminal/stream.zig
@@ -969,43 +969,52 @@ pub fn Stream(comptime Handler: type) type {
                 .change_window_title => |title| {
                     if (@hasDecl(T, "changeWindowTitle")) {
                         try self.handler.changeWindowTitle(title);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .clipboard_contents => |clip| {
                     if (@hasDecl(T, "clipboardContents")) {
                         try self.handler.clipboardContents(clip.kind, clip.data);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .prompt_start => |v| {
-                    if (@hasDecl(T, "promptStart")) switch (v.kind) {
-                        .primary, .right => try self.handler.promptStart(v.aid, v.redraw),
-                        .continuation => try self.handler.promptContinuation(v.aid),
+                    if (@hasDecl(T, "promptStart")) {
+                        switch (v.kind) {
+                            .primary, .right => try self.handler.promptStart(v.aid, v.redraw),
+                            .continuation => try self.handler.promptContinuation(v.aid),
+                        }
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .prompt_end => {
                     if (@hasDecl(T, "promptEnd")) {
                         try self.handler.promptEnd();
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .end_of_input => {
                     if (@hasDecl(T, "endOfInput")) {
                         try self.handler.endOfInput();
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .end_of_command => |end| {
                     if (@hasDecl(T, "endOfCommand")) {
                         try self.handler.endOfCommand(end.exit_code);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .report_pwd => |v| {
                     if (@hasDecl(T, "reportPwd")) {
                         try self.handler.reportPwd(v.value);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
@@ -1017,12 +1026,14 @@ pub fn Stream(comptime Handler: type) type {
                         };
 
                         try self.handler.setMouseShape(shape);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
                 .report_default_color => |v| {
                     if (@hasDecl(T, "reportDefaultColor")) {
                         try self.handler.reportDefaultColor(v.kind, v.terminator);
+                        return;
                     } else log.warn("unimplemented OSC callback: {}", .{cmd});
                 },
 
@@ -1031,6 +1042,13 @@ pub fn Stream(comptime Handler: type) type {
                 else
                     log.warn("unimplemented OSC command: {}", .{cmd}),
             }
+
+            // Fall through for when we don't have a handler.
+            if (@hasDecl(T, "oscUnimplemented")) {
+                try self.handler.oscUnimplemented(cmd);
+            } else {
+                log.warn("unimplemented OSC command: {s}", .{@tagName(cmd)});
+            }
         }
 
         fn configureCharset(
@@ -1598,3 +1616,28 @@ test "stream: insert characters" {
     for ("\x1B[?42@") |c| try s.next(c);
     try testing.expect(!s.handler.called);
 }
+
+test "stream: too many csi params" {
+    const H = struct {
+        pub fn setCursorRight(self: *@This(), v: u16) !void {
+            _ = v;
+            _ = self;
+            unreachable;
+        }
+    };
+
+    var s: Stream(H) = .{ .handler = .{} };
+    try s.nextSlice("\x1B[1;1;1;1;1;1;1;1;1;1;1;1;1;1;1;1;1C");
+}
+
+test "stream: csi param too long" {
+    const H = struct {
+        pub fn setCursorRight(self: *@This(), v: u16) !void {
+            _ = v;
+            _ = self;
+        }
+    };
+
+    var s: Stream(H) = .{ .handler = .{} };
+    try s.nextSlice("\x1B[1111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111C");
+}
diff --git a/src/termio/message.zig b/src/termio/message.zig
index c7fe19976..e2b98c4aa 100644
--- a/src/termio/message.zig
+++ b/src/termio/message.zig
@@ -90,8 +90,9 @@ pub fn MessageData(comptime Elem: type, comptime small_size: comptime_int) type
         pub const Small = struct {
             pub const Max = small_size;
             pub const Array = [Max]Elem;
+            pub const Len = std.math.IntFittingRange(0, small_size);
             data: Array = undefined,
-            len: u8 = 0,
+            len: Len = 0,
         };
 
         pub const Alloc = struct {
@@ -182,3 +183,14 @@ test "MessageData init alloc" {
     try testing.expect(io == .alloc);
     io.alloc.alloc.free(io.alloc.data);
 }
+
+test "MessageData small fits non-u8 sized data" {
+    const testing = std.testing;
+    const alloc = testing.allocator;
+
+    const len = 500;
+    const Data = MessageData(u8, len);
+    const input: []const u8 = "X" ** len;
+    const io = try Data.init(alloc, input);
+    try testing.expect(io == .small);
+}