diff --git a/project.mml b/project.mml
index b28ca603ae..7f7e33151d 100644
--- a/project.mml
+++ b/project.mml
@@ -1455,7 +1455,14 @@ Layer:
             religion,
             tags->'denomination' as denomination,
             tags->'generator:source' as "generator:source",
-            tags->'height' as height,
+            CASE
+              WHEN man_made IN ('mast', 'tower') THEN
+                CASE
+                  WHEN tags->'height' ~ '^-?\d{1,4}(\.\d+)?$' THEN (tags->'height')::NUMERIC
+                  ELSE NULL
+                END
+              ELSE NULL
+            END AS height,
             tags->'power_source' as power_source,
             tags->'icao' as icao,
             tags->'iata' as iata,
@@ -1562,7 +1569,14 @@ Layer:
             religion,
             tags->'denomination' as denomination,
             tags->'generator:source' as "generator:source",
-            tags->'height' as height,
+            CASE
+              WHEN man_made IN ('mast', 'tower') THEN
+                CASE
+                  WHEN tags->'height' ~ '^-?\d{1,4}(\.\d+)?$' THEN (tags->'height')::NUMERIC
+                  ELSE NULL
+                END
+              ELSE NULL
+            END AS height,
             tags->'power_source' as power_source,
             tags->'icao' as icao,
             tags->'iata' as iata,