diff --git a/mclog2psql/main.py b/mclog2psql/main.py
index 8d8c81d..80e18ab 100644
--- a/mclog2psql/main.py
+++ b/mclog2psql/main.py
@@ -109,8 +109,8 @@ class Arguments:
     dir: Path
     password: str | None
     host: str = "localhost"
-    database: str = "minecraft-heatmap"
-    username: str = "minecraft-heatmap"
+    database: str = "minecraft_heatmap"
+    username: str = "minecraft_heatmap"
 
 
 # Source: https://stackoverflow.com/questions/10551117/setting-options-from-environment-variables-when-using-argparse
@@ -152,19 +152,19 @@ def parse_args():
     parser.add_argument(
         "--database",
         type=str,
-        default="minecraft-heatmap",
+        default="minecraft_heatmap",
         action=EnvDefault,
         envvar="MINECRAFT_HEATMAP_DB_NAME",
-        help="Database name (default: minecraft-heatmap).",
+        help="Database name (default: minecraft_heatmap).",
     )
 
     parser.add_argument(
         "--username",
         type=str,
-        default="minecraft-heatmap",
+        default="minecraft_heatmap",
         action=EnvDefault,
         envvar="MINECRAFT_HEATMAP_DB_USER",
-        help="Database username (default: minecraft-heatmap).",
+        help="Database username (default: minecraft_heatmap).",
     )
 
     parser.add_argument(