diff --git a/src/modules/cpus/cortex-m.zig b/src/modules/cpus/cortex-m.zig
index b37e12bf..b9b58289 100644
--- a/src/modules/cpus/cortex-m.zig
+++ b/src/modules/cpus/cortex-m.zig
@@ -70,11 +70,14 @@ pub fn clrex() void {
 pub const startup_logic = struct {
     extern fn microzig_main() noreturn;
 
-    extern var microzig_data_start: anyopaque;
-    extern var microzig_data_end: anyopaque;
-    extern var microzig_bss_start: anyopaque;
-    extern var microzig_bss_end: anyopaque;
-    extern const microzig_data_load_start: anyopaque;
+    // it looks odd to just use a u8 here, but in C it's common to use a
+    // char when linking these values from the linkerscript. What's
+    // important is the addresses of these values.
+    extern var microzig_data_start: u8;
+    extern var microzig_data_end: u8;
+    extern var microzig_bss_start: u8;
+    extern var microzig_bss_end: u8;
+    extern const microzig_data_load_start: u8;
 
     pub fn _start() callconv(.C) noreturn {
 
diff --git a/src/modules/cpus/riscv32.zig b/src/modules/cpus/riscv32.zig
index fea883b7..b7c1b962 100644
--- a/src/modules/cpus/riscv32.zig
+++ b/src/modules/cpus/riscv32.zig
@@ -47,11 +47,14 @@ pub const REGBYTES = (1 << LOG_REGBYTES);
 pub const startup_logic = struct {
     extern fn microzig_main() noreturn;
 
-    extern var microzig_data_start: anyopaque;
-    extern var microzig_data_end: anyopaque;
-    extern var microzig_bss_start: anyopaque;
-    extern var microzig_bss_end: anyopaque;
-    extern const microzig_data_load_start: anyopaque;
+    // it looks odd to just use a u8 here, but in C it's common to use a
+    // char when linking these values from the linkerscript. What's
+    // important is the addresses of these values.
+    extern var microzig_data_start: u8;
+    extern var microzig_data_end: u8;
+    extern var microzig_bss_start: u8;
+    extern var microzig_bss_end: u8;
+    extern const microzig_data_load_start: u8;
 
     pub fn _start() callconv(.C) noreturn {
 
diff --git a/src/start.zig b/src/start.zig
index 59ec4cd4..7271ad29 100644
--- a/src/start.zig
+++ b/src/start.zig
@@ -127,11 +127,14 @@ export fn microzig_main() noreturn {
 /// Contains references to the microzig .data and .bss sections, also
 /// contains the initial load address for .data if it is in flash.
 pub const sections = struct {
-    extern var microzig_data_start: anyopaque;
-    extern var microzig_data_end: anyopaque;
-    extern var microzig_bss_start: anyopaque;
-    extern var microzig_bss_end: anyopaque;
-    extern const microzig_data_load_start: anyopaque;
+    // it looks odd to just use a u8 here, but in C it's common to use a
+    // char when linking these values from the linkerscript. What's
+    // important is the addresses of these values.
+    extern var microzig_data_start: u8;
+    extern var microzig_data_end: u8;
+    extern var microzig_bss_start: u8;
+    extern var microzig_bss_end: u8;
+    extern const microzig_data_load_start: u8;
 };
 
 pub fn initialize_system_memories() void {