diff --git a/osmxml.py b/osmxml.py
index 3826b0a..c90879c 100644
--- a/osmxml.py
+++ b/osmxml.py
@@ -203,6 +203,19 @@ class mstr_osmxml:
 
         # Return the found surface type
         return surface
+    
+
+    # Again, a crash on number checking of levels.
+    # Short call for sanity check
+    def is_float(element: any) -> bool:
+        #If you expect None to be passed:
+        if element is None: 
+            return False
+        try:
+            float(element)
+            return True
+        except ValueError:
+            return False
 
 
     # Find the levels of a building (for shadow rendering)
@@ -217,8 +230,9 @@ class mstr_osmxml:
                     a = tag.getAttribute("k")
                     v = tag.getAttribute("v")
                     if a == "building:levels":
-                        lvl = int(float(v)) # <- This blew layergen and maskgen at some buildings with 1.5 floors
-                        break
+                        if self.is_float(v) == True:
+                            lvl = int(float(v)) # <- This blew layergen and maskgen at some buildings with 1.5 floors
+                            break
         return lvl
     
     # Find minimum level of a building