diff --git a/scripts/dbgbmap.py b/scripts/dbgbmap.py
index 9eb7b3fd..cbf0d82c 100755
--- a/scripts/dbgbmap.py
+++ b/scripts/dbgbmap.py
@@ -4598,11 +4598,11 @@ def main_(ring, disk, mroots=None, *,
             # well for things that are often powers-of-two
             block_cols_ = 1
             block_rows_ = len(bmap)
-            while (abs(((canvas.width/(block_cols_ * 2))
-                            / (canvas.height/mt.ceil(block_rows_ / 2)))
+            while (abs(((canvas.width/(block_cols_*2))
+                            / max(canvas.height/mt.ceil(block_rows_/2), 1))
                         - block_ratio)
                     < abs(((canvas.width/block_cols_)
-                            / (canvas.height/block_rows_)))
+                            / max(canvas.height/block_rows_, 1)))
                         - block_ratio):
                 block_cols_ *= 2
                 block_rows_ = mt.ceil(block_rows_ / 2)
diff --git a/scripts/dbgbmapd3.py b/scripts/dbgbmapd3.py
index 795fd3b6..352ec076 100755
--- a/scripts/dbgbmapd3.py
+++ b/scripts/dbgbmapd3.py
@@ -4918,11 +4918,11 @@ def main(disk, output, mroots=None, *,
         # well for things that are often powers-of-two
         block_cols_ = 1
         block_rows_ = len(bmap)
-        while (abs(((width__/(block_cols_ * 2))
-                        / (height__/mt.ceil(block_rows_ / 2)))
+        while (abs(((width__/(block_cols_*2))
+                        / max(height__/mt.ceil(block_rows_/2), 1))
                     - block_ratio)
                 < abs(((width__/block_cols_)
-                        / (height__/block_rows_)))
+                        / max(height__/block_rows_, 1)))
                     - block_ratio):
             block_cols_ *= 2
             block_rows_ = mt.ceil(block_rows_ / 2)
diff --git a/scripts/tracebd.py b/scripts/tracebd.py
index d5789836..4aa3aefb 100755
--- a/scripts/tracebd.py
+++ b/scripts/tracebd.py
@@ -1794,11 +1794,11 @@ def main(path='-', *,
                 # well for things that are often powers-of-two
                 block_cols_ = 1
                 block_rows_ = len(bmap)
-                while (abs(((canvas.width/(block_cols_ * 2))
-                                / (canvas.height/mt.ceil(block_rows_ / 2)))
+                while (abs(((canvas.width/(block_cols_*2))
+                                / max(canvas.height/mt.ceil(block_rows_/2), 1))
                             - block_ratio)
                         < abs(((canvas.width/block_cols_)
-                                / (canvas.height/block_rows_)))
+                                / max(canvas.height/block_rows_, 1)))
                             - block_ratio):
                     block_cols_ *= 2
                     block_rows_ = mt.ceil(block_rows_ / 2)