diff --git a/examples/benchmarks/platform/host.zig b/examples/benchmarks/platform/host.zig
index 33b9fdd740..857dc3b43d 100644
--- a/examples/benchmarks/platform/host.zig
+++ b/examples/benchmarks/platform/host.zig
@@ -150,7 +150,7 @@ pub export fn roc_fx_putInt(int: i64) i64 {
     return 0;
 }
 
-export fn roc_fx_putLine(rocPath: str.RocStr) callconv(.C) void {
+export fn roc_fx_putLine(rocPath: *str.RocStr) callconv(.C) void {
     const stdout = std.io.getStdOut().writer();
 
     for (rocPath.asSlice()) |char| {
diff --git a/examples/hello-world/c-platform/host.c b/examples/hello-world/c-platform/host.c
index d685f605c1..a096367dd5 100644
--- a/examples/hello-world/c-platform/host.c
+++ b/examples/hello-world/c-platform/host.c
@@ -54,10 +54,12 @@ size_t roc_str_len(struct RocStr str) {
   }
 }
 
-extern struct RocStr roc__mainForHost_1_exposed();
+extern void roc__mainForHost_1_exposed_generic(*RocStr);
 
 int main() {
-  struct RocStr str = roc__mainForHost_1_exposed();
+
+  struct RocStr str;
+  roc__mainForHost_1_exposed_generic(&str);
 
   // Determine str_len and the str_bytes pointer,
   // taking into account the small string optimization.
diff --git a/examples/hello-world/rust-platform/src/lib.rs b/examples/hello-world/rust-platform/src/lib.rs
index 5c90b91be8..7df8fe563c 100644
--- a/examples/hello-world/rust-platform/src/lib.rs
+++ b/examples/hello-world/rust-platform/src/lib.rs
@@ -6,8 +6,8 @@ use std::ffi::CStr;
 use std::os::raw::c_char;
 
 extern "C" {
-    #[link_name = "roc__mainForHost_1_exposed"]
-    fn roc_main() -> RocStr;
+    #[link_name = "roc__mainForHost_1_exposed_generic"]
+    fn roc_main(_: &mut RocStr);
 }
 
 #[no_mangle]
@@ -56,7 +56,8 @@ pub unsafe extern "C" fn roc_memset(dst: *mut c_void, c: i32, n: usize) -> *mut
 #[no_mangle]
 pub extern "C" fn rust_main() -> i32 {
     unsafe {
-        let roc_str = roc_main();
+        let mut roc_str = RocStr::default();
+        roc_main(&mut roc_str);
 
         let len = roc_str.len();
         let str_bytes = roc_str.as_bytes().as_ptr() as *const libc::c_void;
diff --git a/examples/hello-world/zig-platform/host.zig b/examples/hello-world/zig-platform/host.zig
index d30eccfbfe..f20686dcb0 100644
--- a/examples/hello-world/zig-platform/host.zig
+++ b/examples/hello-world/zig-platform/host.zig
@@ -77,7 +77,7 @@ export fn roc_memset(dst: [*]u8, value: i32, size: usize) callconv(.C) void {
 const mem = std.mem;
 const Allocator = mem.Allocator;
 
-extern fn roc__mainForHost_1_exposed() RocStr;
+extern fn roc__mainForHost_1_exposed_generic(*RocStr) void;
 
 const Unit = extern struct {};
 
@@ -90,7 +90,8 @@ pub fn main() u8 {
     std.os.clock_gettime(std.os.CLOCK_REALTIME, &ts1) catch unreachable;
 
     // actually call roc to populate the callresult
-    var callresult = roc__mainForHost_1_exposed();
+    var callresult = RocStr.empty();
+    roc__mainForHost_1_exposed_generic(&callresult);
 
     // end time
     var ts2: std.os.timespec = undefined;