diff --git a/psrdada_cpp/effelsberg/edd/Unpacker.cuh b/psrdada_cpp/effelsberg/edd/Unpacker.cuh
index 1fb83db4630d0d8bd238168eebee5d34fe4d4f59..e8fcc2a0fa2ffc861d12cae777a92a661bd7faba 100644
--- a/psrdada_cpp/effelsberg/edd/Unpacker.cuh
+++ b/psrdada_cpp/effelsberg/edd/Unpacker.cuh
@@ -10,10 +10,10 @@ namespace edd {
 namespace kernels {
 
 __global__
-void unpack_edd_12bit_to_float32(uint64_t* __restrict__ in, float* __restrict__ out, int n);
+void unpack_edd_12bit_to_float32(uint64_t const* __restrict__ in, float* __restrict__ out, int n);
 
 __global__
-void unpack_edd_8bit_to_float32(uint64_t* __restrict__ in, float* __restrict__ out, int n);
+void unpack_edd_8bit_to_float32(uint64_t const* __restrict__ in, float* __restrict__ out, int n);
 
 }
 
diff --git a/psrdada_cpp/effelsberg/edd/src/Unpacker.cu b/psrdada_cpp/effelsberg/edd/src/Unpacker.cu
index e9ac9de4af3a250c413f1c86231fc3c633ca62ed..88d428861bde0c8b12059fa747e0f07d81ff18ef 100644
--- a/psrdada_cpp/effelsberg/edd/src/Unpacker.cu
+++ b/psrdada_cpp/effelsberg/edd/src/Unpacker.cu
@@ -22,7 +22,7 @@ __device__ __forceinline__ uint64_t swap64(uint64_t x)
 }
 
 __global__
-void unpack_edd_12bit_to_float32(uint64_t* __restrict__ in, float* __restrict__ out, int n)
+void unpack_edd_12bit_to_float32(uint64_t const* __restrict__ in, float* __restrict__ out, int n)
 {
     /**
      * Note: This kernels will not work with more than 512 threads.
@@ -74,7 +74,7 @@ void unpack_edd_12bit_to_float32(uint64_t* __restrict__ in, float* __restrict__
 }
 
 __global__
-void unpack_edd_8bit_to_float32(uint64_t* __restrict__ in, float* __restrict__ out, int n)
+void unpack_edd_8bit_to_float32(uint64_t const* __restrict__ in, float* __restrict__ out, int n)
 {
     /**
      * Note: This kernels will not work with more than 512 threads.