diff --git a/.github/workflows/ports.yml b/.github/workflows/ports.yml
index 26246a1ee..60f552390 100644
--- a/.github/workflows/ports.yml
+++ b/.github/workflows/ports.yml
@@ -96,12 +96,10 @@ jobs:
       working-directory: examples/gigadevice/gd32
 
     - name: microchip/atmega
-      if: 0 # https://codeberg.org/ziglang/zig/issues/32108
       run: zig build -Doptimize=ReleaseSmall
       working-directory: examples/microchip/atmega
 
     - name: microchip/attiny
-      if: 0 # https://codeberg.org/ziglang/zig/issues/32108
       run: zig build -Doptimize=ReleaseSmall
       working-directory: examples/microchip/attiny
 
diff --git a/core/src/cpus/avr_common.zig b/core/src/cpus/avr_common.zig
index b85122329..a9173e6c8 100644
--- a/core/src/cpus/avr_common.zig
+++ b/core/src/cpus/avr_common.zig
@@ -17,9 +17,16 @@ pub const interrupt = struct {
 };
 
 /// AVR interrupt handler function type.
-pub const HandlerFn = extern union {
+pub const HandlerFn = union(enum) {
+    /// Standard AVR interrupt handler. Disables global interrupts while it is
+    /// executing. Compiler generates prologue for pushing clobbered registers to
+    /// the stack, and corresponding epilogue with `reti` intsruction for
+    /// returning from an interrupt.
     signal: *const fn () callconv(.avr_signal) void,
+    /// Similar to the signal calling convention, but global interrupts are
+    /// enabled in the prologue, allowing for nested interrupts.
     interrupt: *const fn () callconv(.avr_interrupt) void,
+    /// No prologue, no epilogue, best for handwritten assembly.
     naked: *const fn () callconv(.naked) noreturn,
 };
 
@@ -78,8 +85,8 @@ pub fn generate_vector_table_asm(comptime jump_insn: JumpInstruction) []const u8
     for (field_names[1..]) |field_name| {
         const handler = @field(interrupt_options, field_name);
         if (handler) |func| {
-            const isr = make_isr_handler(field_name, func);
-            asm_str = asm_str ++ jump_insn.to_string() ++ isr.exported_name ++ "\n";
+            const isr_symbol = export_isr_handler(field_name, func);
+            asm_str = asm_str ++ jump_insn.to_string() ++ " " ++ isr_symbol ++ "\n";
         } else {
             asm_str = asm_str ++ jump_insn.to_string() ++ " microzig_unhandled_vector\n";
         }
@@ -88,28 +95,14 @@ pub fn generate_vector_table_asm(comptime jump_insn: JumpInstruction) []const u8
     return asm_str;
 }
 
-fn make_isr_handler(comptime name: []const u8, comptime func: anytype) type {
-    const calling_convention = switch (@typeInfo(@TypeOf(func))) {
-        .@"fn" => |info| info.calling_convention,
-        .pointer => |info| switch (@typeInfo(info.child)) {
-            .@"fn" => |fn_info| fn_info.calling_convention,
-            else => @compileError("Declarations in 'interrupts' namespace must all be functions. '" ++ name ++ "' is not a function"),
-        },
-        else => @compileError("Declarations in 'interrupts' namespace must all be functions. '" ++ name ++ "' is not a function"),
-    };
-
-    switch (calling_convention) {
-        .auto, .avr_signal, .avr_interrupt => {},
-        else => @compileError("Calling conventions for interrupts must be 'avr_interrupt', 'avr_signal', or unspecified. The avr_signal calling convention leaves global interrupts disabled during the ISR, where avr_interrupt enables global interrupts for nested ISRs."),
-    }
+fn export_isr_handler(comptime name: []const u8, comptime handler: HandlerFn) []const u8 {
+    const exported_name = "microzig_isr_" ++ name;
 
-    return struct {
-        pub const exported_name = "microzig_isr_" ++ name;
+    switch (handler) {
+        inline else => |func| @export(func, .{ .name = exported_name }),
+    }
 
-        comptime {
-            @export(func, .{ .name = exported_name });
-        }
-    };
+    return exported_name;
 }
 
 pub const startup_logic = struct {
diff --git a/examples/microchip/attiny/build.zig b/examples/microchip/attiny/build.zig
index df2730852..9bb152f85 100644
--- a/examples/microchip/attiny/build.zig
+++ b/examples/microchip/attiny/build.zig
@@ -16,7 +16,6 @@ pub fn build(b: *std.Build) void {
         .{ .target = mb.ports.attiny.boards.digispark, .name = "digispark_blinky", .file = "src/blinky.zig" },
         .{ .target = mb.ports.attiny.boards.adafruit.trinket, .name = "trinket_blinky", .file = "src/blinky.zig" },
         .{ .target = mb.ports.attiny.boards.adafruit.gemma, .name = "gemma_blinky", .file = "src/blinky.zig" },
-        .{ .target = mb.ports.attiny.chips.attiny85, .name = "attiny85_blinky", .file = "src/blinky.zig" },
         .{ .target = mb.ports.attiny.chips.attiny85, .name = "attiny85_blinky_interrupt", .file = "src/blinky_interrupt.zig" },
         .{ .target = mb.ports.attiny.chips.attiny84, .name = "attiny84_blinky", .file = "src/blinky84.zig" },
         .{ .target = mb.ports.attiny.chips.attiny1634, .name = "attiny1634_pwm_adc", .file = "src/attiny1634_pwm_adc.zig" },
diff --git a/examples/microchip/attiny/src/attiny1616_tca_rtc.zig b/examples/microchip/attiny/src/attiny1616_tca_rtc.zig
index 8d7807d82..aa4e7fab0 100644
--- a/examples/microchip/attiny/src/attiny1616_tca_rtc.zig
+++ b/examples/microchip/attiny/src/attiny1616_tca_rtc.zig
@@ -7,6 +7,10 @@ const aux_led = hal.gpio.pin(.b, 5);
 const switch_pin = hal.gpio.pin(.a, 5);
 const Ramp = hal.progmem.Table(u8, 4, .{ 1, 4, 16, 64 });
 
+comptime {
+    _ = microzig.export_startup();
+}
+
 pub fn main() void {
     hal.clock.use_default20_m_hz_div2();
 
diff --git a/examples/microchip/attiny/src/attiny1634_pwm_adc.zig b/examples/microchip/attiny/src/attiny1634_pwm_adc.zig
index 6c0c9e3b4..77fe76a22 100644
--- a/examples/microchip/attiny/src/attiny1634_pwm_adc.zig
+++ b/examples/microchip/attiny/src/attiny1634_pwm_adc.zig
@@ -7,6 +7,10 @@ const fet_pwm = hal.gpio.pin(.c, 0);
 const voltage = hal.gpio.pin(.b, 1);
 const Gamma = hal.progmem.Table(u8, 4, .{ 0, 8, 32, 255 });
 
+comptime {
+    _ = microzig.export_startup();
+}
+
 pub fn main() void {
     ch1_pwm.set_direction(.output);
     ch2_pwm.set_direction(.output);
diff --git a/examples/microchip/attiny/src/blinky.zig b/examples/microchip/attiny/src/blinky.zig
index 8e49f0467..78e7c3c41 100644
--- a/examples/microchip/attiny/src/blinky.zig
+++ b/examples/microchip/attiny/src/blinky.zig
@@ -3,6 +3,10 @@ const microzig = @import("microzig");
 
 const led_pin = microzig.board.led_pin;
 
+comptime {
+    _ = microzig.export_startup();
+}
+
 pub fn main() void {
     led_pin.set_direction(.output);
 
diff --git a/examples/microchip/attiny/src/blinky84.zig b/examples/microchip/attiny/src/blinky84.zig
index 443fba4f0..d4900d8b0 100644
--- a/examples/microchip/attiny/src/blinky84.zig
+++ b/examples/microchip/attiny/src/blinky84.zig
@@ -2,6 +2,10 @@ const std = @import("std");
 const microzig = @import("microzig");
 const gpio = microzig.hal.gpio;
 
+comptime {
+    _ = microzig.export_startup();
+}
+
 // ATtiny84: use PA0 as the LED pin
 const led_pin = gpio.pin(.a, 0);
 
@@ -22,7 +26,7 @@ pub fn busy_sleep(comptime limit: comptime_int) void {
         bits += 1;
     }
 
-    const I = std.meta.Int(.unsigned, bits);
+    const I = @Int(.unsigned, bits);
 
     var i: I = 0;
     while (i < limit) : (i += 1) {
diff --git a/examples/microchip/attiny/src/blinky_interrupt.zig b/examples/microchip/attiny/src/blinky_interrupt.zig
index 7034fff78..e34b09973 100644
--- a/examples/microchip/attiny/src/blinky_interrupt.zig
+++ b/examples/microchip/attiny/src/blinky_interrupt.zig
@@ -2,11 +2,15 @@ const std = @import("std");
 const microzig = @import("microzig");
 const gpio = microzig.hal.gpio;
 
+comptime {
+    _ = microzig.export_startup();
+}
+
 const led_pin = gpio.pin(.b, 1);
 
 pub const microzig_options: microzig.Options = .{
     .interrupts = .{
-        .INT0 = &my_int0_handler,
+        .INT0 = .{ .signal = &my_int0_handler },
     },
 };
 
diff --git a/port/microchip/attiny/src/boards/adafruit_gemma.zig b/port/microchip/attiny/src/boards/adafruit_gemma.zig
index 24da7ac8c..74307ab8d 100644
--- a/port/microchip/attiny/src/boards/adafruit_gemma.zig
+++ b/port/microchip/attiny/src/boards/adafruit_gemma.zig
@@ -1,13 +1,8 @@
-pub const chip = @import("chip");
+const microzig = @import("microzig");
+const gpio = microzig.hal.gpio;
 
 pub const clock_frequencies = .{
     .cpu = 8_000_000,
 };
 
-pub const pin_map = .{
-    .D0 = "PB0",
-    .D1 = "PB1",
-    .D2 = "PB2",
-    // Built-in LED on D1 (PB1)
-    .LED = "PB1",
-};
+pub const led_pin = gpio.pin(.b, 1);
diff --git a/port/microchip/attiny/src/boards/digispark.zig b/port/microchip/attiny/src/boards/digispark.zig
index 8245210fc..54cc4a7bb 100644
--- a/port/microchip/attiny/src/boards/digispark.zig
+++ b/port/microchip/attiny/src/boards/digispark.zig
@@ -1,17 +1,8 @@
-pub const chip = @import("chip");
+const microzig = @import("microzig");
+const gpio = microzig.hal.gpio;
 
 pub const clock_frequencies = .{
     .cpu = 16_500_000,
 };
 
-pub const pin_map = .{
-    // Digispark pin numbering maps to PORTB
-    .P0 = "PB0",
-    .P1 = "PB1",
-    .P2 = "PB2",
-    .P3 = "PB3",
-    .P4 = "PB4",
-    .P5 = "PB5",
-    // Built-in LED on P1 (PB1)
-    .LED = "PB1",
-};
+pub const led_pin = gpio.pin(.b, 1);