diff --git a/src/runtime/src/kernel/dma.rs b/src/runtime/src/kernel/dma.rs
index a19d95f5..9151cddd 100644
--- a/src/runtime/src/kernel/dma.rs
+++ b/src/runtime/src/kernel/dma.rs
@@ -116,7 +116,7 @@ pub extern fn dma_record_output(target: i32, word: i32) {
     }
 }
 
-pub extern fn dma_record_output_wide(target: i32, words: CSlice<i32>) {
+pub extern fn dma_record_output_wide(target: i32, words: &CSlice<i32>) {
     assert!(words.len() <= 16); // enforce the hardware limit
 
     unsafe {
diff --git a/src/runtime/src/rtio_csr.rs b/src/runtime/src/rtio_csr.rs
index 761dcbe2..b08c90e1 100644
--- a/src/runtime/src/rtio_csr.rs
+++ b/src/runtime/src/rtio_csr.rs
@@ -94,7 +94,7 @@ pub extern fn output(target: i32, data: i32) {
     }
 }
 
-pub extern fn output_wide(target: i32, data: CSlice<i32>) {
+pub extern fn output_wide(target: i32, data: &CSlice<i32>) {
     unsafe {
         csr::rtio::target_write(target as u32);
         // writing target clears o_data