diff --git a/tests/test_shared_memory.py b/tests/test_shared_memory.py
index 31156d6..b010cdd 100644
--- a/tests/test_shared_memory.py
+++ b/tests/test_shared_memory.py
@@ -47,7 +47,7 @@ class TestElement(xo.HybridClass):
                   unsigned int gid = blockIdx.x*blockDim.x + threadIdx.x;  // global thread ID: 0,1,2,3
 
                   // init shared memory with chunk of input array
-                  extern __shared__ double sdata[2];
+                  extern __shared__ double sdata[];
                   sdata[tid] = input_arr[gid];
                   __syncthreads();
 
diff --git a/xobjects/context_cupy.py b/xobjects/context_cupy.py
index 3838376..5ba68e6 100644
--- a/xobjects/context_cupy.py
+++ b/xobjects/context_cupy.py
@@ -352,15 +352,22 @@ def __invert__(self):
 
 cudaheader: List[SourceType] = [
     """\
-typedef signed long long   int64_t;  //only_for_context cuda
 typedef signed int         int32_t;  //only_for_context cuda
 typedef signed short       int16_t;  //only_for_context cuda
 typedef signed char        int8_t;   //only_for_context cuda
-typedef unsigned long long uint64_t; //only_for_context cuda
 typedef unsigned int       uint32_t; //only_for_context cuda
 typedef unsigned short     uint16_t; //only_for_context cuda
 typedef unsigned char      uint8_t;  //only_for_context cuda
 
+#if defined(__CUDACC__) && !defined(__HIPCC__)
+typedef signed long long   int64_t;
+typedef unsigned long long uint64_t;
+#endif
+
+#ifndef NULL
+  #define NULL nullptr
+#endif
+
 """
 ]
 
diff --git a/xobjects/headers/atomicadd.h b/xobjects/headers/atomicadd.h
index 6782705..89e4f83 100644
--- a/xobjects/headers/atomicadd.h
+++ b/xobjects/headers/atomicadd.h
@@ -101,7 +101,7 @@ DEF_ATOMIC_ADD(double  , f64)
 // -------------------------------------------
 #if defined(XO_CONTEXT_CUDA)
     // CUDA compiler may not have <stdint.h>, so define the types if needed.
-    #ifdef __CUDACC_RTC__
+    #if defined(__CUDACC_RTC__) && !defined(__HIPCC__)
         // NVRTC (CuPy RawModule default) can’t see <stdint.h>, so detect it via __CUDACC_RTC__
         typedef signed char        int8_t;
         typedef short              int16_t;
@@ -111,6 +111,14 @@ DEF_ATOMIC_ADD(double  , f64)
         typedef unsigned short     uint16_t;
         typedef unsigned int       uint32_t;
         typedef unsigned long long uint64_t;
+    #elif defined(__HIPCC__) && !defined(__CUDACC_RTC__)
+        // ROCm appears to have definitions for 64-bit int types
+        typedef signed char        int8_t;
+        typedef short              int16_t;
+        typedef int                int32_t;
+        typedef unsigned char      uint8_t;
+        typedef unsigned short     uint16_t;
+        typedef unsigned int       uint32_t;
     #else
         // Alternatively, NVCC path is fine with host headers
         #include <stdint.h>