diff --git a/src/scgenerator/math.py b/src/scgenerator/math.py
index 8072d77..5a72267 100644
--- a/src/scgenerator/math.py
+++ b/src/scgenerator/math.py
@@ -3,6 +3,7 @@ collection of purely mathematical function
 """
 
 import math
+import warnings
 from dataclasses import dataclass
 from functools import cache
 from typing import Sequence
@@ -142,12 +143,15 @@ def to_dB(arr: np.ndarray, ref=None, axis=None) -> np.ndarray:
     if axis is not None and arr.ndim > 1 and ref is None:
         return np.apply_along_axis(to_dB, axis, arr)
 
+    out = np.ones_like(arr)
     if ref is None:
         ref = np.max(arr)
+    above_0 = arr > 0
+    if not np.any(above_0) or ref <= 0:
+        warnings.warn("invalid array to convert to dB, returning 0 instead")
+        return out
     m = arr / ref
-    above_0 = m > 0
-    m = 10 * np.log10(m, out=np.ones_like(m) * (10 * np.log10(m[above_0].min())), where=above_0)
-    return m
+    return 10 * np.log10(m, out=out * (10 * np.log10(m[above_0].min())), where=above_0)
 
 
 def u_nm(n, m):