diff --git a/pyproject.toml b/pyproject.toml
index 0b7822c6..b04cc08c 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -11,7 +11,7 @@ license = "MIT"
 
 [tool.poetry.dependencies]
 python = ">=3.7"
-numpy = ">=1.10.1,<2.0.0"
+numpy = ">=2.0.0"
 scipy = ">=1.0.0"
 pandas = ">=1.3.0"
 SoundFile = ">=0.10.0"
diff --git a/wfdb/io/_signal.py b/wfdb/io/_signal.py
index 68ca57e4..0171291d 100644
--- a/wfdb/io/_signal.py
+++ b/wfdb/io/_signal.py
@@ -2312,6 +2312,8 @@ def wr_dat_file(
         # Non-expanded format always has 1 sample per frame
         n_sig = d_signal.shape[1]
         samps_per_frame = [1] * n_sig
+    
+    d_signal = d_signal.astype("int64")
 
     # Total number of samples per frame (equal to number of signals if
     # expanded=False, but may be greater for expanded=True)
diff --git a/wfdb/io/annotation.py b/wfdb/io/annotation.py
index b398fa07..4d451b19 100644
--- a/wfdb/io/annotation.py
+++ b/wfdb/io/annotation.py
@@ -2237,7 +2237,7 @@ def proc_core_fields(filebytes, bpi):
 
     # Not a skip - it is the actual sample number + annotation type store value
     label_store = filebytes[bpi, 1] >> 2
-    sample_diff += int(filebytes[bpi, 0] + 256 * (filebytes[bpi, 1] & 3))
+    sample_diff += int(filebytes[bpi, 0]) + 256 * int(filebytes[bpi, 1] & 3)
     bpi = bpi + 1
 
     return sample_diff, label_store, bpi