diff --git a/pygmt/src/grdhisteq.py b/pygmt/src/grdhisteq.py
index 0365f5238dc..352c83cfe9a 100644
--- a/pygmt/src/grdhisteq.py
+++ b/pygmt/src/grdhisteq.py
@@ -243,7 +243,7 @@ def compute_bins(
                 dtype={
                     "start": np.float32,
                     "stop": np.float32,
-                    "bin_id": np.uint32,
+                    "bin_id": np.int64,
                 },
                 index_col="bin_id" if output_type == "pandas" else None,
             )
diff --git a/pygmt/tests/test_grdhisteq.py b/pygmt/tests/test_grdhisteq.py
index 76892905269..56e74253f4f 100644
--- a/pygmt/tests/test_grdhisteq.py
+++ b/pygmt/tests/test_grdhisteq.py
@@ -53,7 +53,7 @@ def fixture_expected_df():
     return pd.DataFrame(
         data=np.array([[345.5, 519.5, 0], [519.5, 726.5, 1]]),
         columns=["start", "stop", "bin_id"],
-    ).astype({"start": np.float32, "stop": np.float32, "bin_id": np.uint32})
+    ).astype({"start": np.float32, "stop": np.float32, "bin_id": np.int64})
 
 
 def test_equalize_grid_outgrid_file(grid, expected_grid, region):