diff --git a/klamath_rs_ext/basic.py b/klamath_rs_ext/basic.py
index 4540fe6..aabc246 100644
--- a/klamath_rs_ext/basic.py
+++ b/klamath_rs_ext/basic.py
@@ -32,7 +32,7 @@ CONV_TABLE_i32 = {
 
 
 def pack_int2(data: NDArray[numpy.integer] | Sequence[int] | int) -> bytes:
-    arr = numpy.asarray(data)
+    arr = numpy.atleast_1d(data)
 
     for dtype in CONV_TABLE_i16.keys():
         if arr.dtype != dtype:
@@ -43,7 +43,8 @@ def pack_int2(data: NDArray[numpy.integer] | Sequence[int] | int) -> bytes:
             arr = numpy.array(arr, copy=True)
 
         fn = CONV_TABLE_i16[dtype]
-        result = fn(ffi.from_buffer(arr), arr.size)
+        buf = ffi.from_buffer(ffi.typeof(fn).args[0], arr, require_writable=True)
+        result = fn(buf, arr.size)
 
         if result != 0:
             raise ValueError(f'Invalid value for conversion to Int2: {result}')
@@ -61,7 +62,7 @@ def pack_int2(data: NDArray[numpy.integer] | Sequence[int] | int) -> bytes:
 
 
 def pack_int4(data: NDArray[numpy.integer] | Sequence[int] | int) -> bytes:
-    arr = numpy.asarray(data)
+    arr = numpy.atleast_1d(data)
 
     for dtype in CONV_TABLE_i32.keys():
         if arr.dtype != dtype:
@@ -72,7 +73,8 @@ def pack_int4(data: NDArray[numpy.integer] | Sequence[int] | int) -> bytes:
             arr = numpy.array(arr, copy=True)
 
         fn = CONV_TABLE_i32[dtype]
-        result = fn(ffi.from_buffer(arr), arr.size)
+        buf = ffi.from_buffer(ffi.typeof(fn).args[0], arr, require_writable=True)
+        result = fn(buf, arr.size)
 
         if result != 0:
             raise ValueError(f'Invalid value for conversion to Int4: {result}')