diff --git a/Cargo.toml b/Cargo.toml
index bf4f71c7..af9c719e 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -740,9 +740,6 @@ significant_drop_tightening = { level = "allow", priority = 1 }      # TODO
 pedantic = "warn"
 
 ## some sadness
-cast_possible_truncation = { level = "allow", priority = 1 }
-cast_precision_loss = { level = "allow", priority = 1 }
-cast_sign_loss = { level = "allow", priority = 1 }
 doc_markdown = { level = "allow", priority = 1 }
 enum_glob_use = { level = "allow", priority = 1 }
 error_impl_error = { level = "allow", priority = 1 }
diff --git a/src/core/utils/math.rs b/src/core/utils/math.rs
index 3dc7e27f..155721e7 100644
--- a/src/core/utils/math.rs
+++ b/src/core/utils/math.rs
@@ -60,7 +60,8 @@ pub fn usize_from_f64(val: f64) -> Result<usize, Error> {
 		return Err(Error::Arithmetic("Converting negative float to unsigned integer"));
 	}
 
-	Ok(val as usize)
+	//SAFETY: <https://doc.rust-lang.org/std/primitive.f64.html#method.to_int_unchecked>
+	Ok(unsafe { val.to_int_unchecked::<usize>() })
 }
 
 #[inline]
@@ -83,5 +84,5 @@ pub fn ruma_from_usize(val: usize) -> ruma::UInt {
 
 #[inline]
 #[must_use]
-#[allow(clippy::as_conversions)]
+#[allow(clippy::as_conversions, clippy::cast_possible_truncation)]
 pub fn usize_from_u64_truncated(val: u64) -> usize { val as usize }
diff --git a/src/core/utils/time.rs b/src/core/utils/time.rs
index bf6192b2..9a31632e 100644
--- a/src/core/utils/time.rs
+++ b/src/core/utils/time.rs
@@ -2,7 +2,7 @@ use std::time::{Duration, SystemTime, UNIX_EPOCH};
 
 #[inline]
 #[must_use]
-#[allow(clippy::as_conversions)]
+#[allow(clippy::as_conversions, clippy::cast_possible_truncation)]
 pub fn now_millis() -> u64 {
 	UNIX_EPOCH
 		.elapsed()
@@ -28,7 +28,7 @@ pub fn format(ts: SystemTime, str: &str) -> String {
 }
 
 #[must_use]
-#[allow(clippy::as_conversions)]
+#[allow(clippy::as_conversions, clippy::cast_possible_truncation, clippy::cast_sign_loss)]
 pub fn pretty(d: Duration) -> String {
 	use Unit::*;
 
@@ -50,7 +50,7 @@ pub fn pretty(d: Duration) -> String {
 /// part is the largest Unit containing a non-zero value, the frac part is a
 /// rational remainder left over.
 #[must_use]
-#[allow(clippy::as_conversions)]
+#[allow(clippy::as_conversions, clippy::cast_precision_loss)]
 pub fn whole_and_frac(d: Duration) -> (Unit, f64) {
 	use Unit::*;
 
diff --git a/src/database/engine.rs b/src/database/engine.rs
index 7c9522e1..53e39abc 100644
--- a/src/database/engine.rs
+++ b/src/database/engine.rs
@@ -134,23 +134,21 @@ impl Engine {
 			.fetch_sub(1, std::sync::atomic::Ordering::Relaxed);
 	}
 
-	#[allow(clippy::as_conversions, clippy::cast_sign_loss, clippy::cast_possible_truncation)]
 	pub fn memory_usage(&self) -> Result<String> {
 		let mut res = String::new();
 		let stats = get_memory_usage_stats(Some(&[&self.db]), Some(&[&self.row_cache])).or_else(or_else)?;
+		let mibs = |input| f64::from(u32::try_from(input / 1024).unwrap_or(0)) / 1024.0;
 		writeln!(
 			res,
 			"Memory buffers: {:.2} MiB\nPending write: {:.2} MiB\nTable readers: {:.2} MiB\nRow cache: {:.2} MiB",
-			stats.mem_table_total as f64 / 1024.0 / 1024.0,
-			stats.mem_table_unflushed as f64 / 1024.0 / 1024.0,
-			stats.mem_table_readers_total as f64 / 1024.0 / 1024.0,
-			self.row_cache.get_usage() as f64 / 1024.0 / 1024.0,
-		)
-		.expect("should be able to write to string buffer");
+			mibs(stats.mem_table_total),
+			mibs(stats.mem_table_unflushed),
+			mibs(stats.mem_table_readers_total),
+			mibs(u64::try_from(self.row_cache.get_usage())?),
+		)?;
 
 		for (name, cache) in &*self.col_cache.read().expect("locked") {
-			writeln!(res, "{} cache: {:.2} MiB", name, cache.get_usage() as f64 / 1024.0 / 1024.0,)
-				.expect("should be able to write to string buffer");
+			writeln!(res, "{} cache: {:.2} MiB", name, mibs(u64::try_from(cache.get_usage())?))?;
 		}
 
 		Ok(res)
@@ -214,8 +212,7 @@ impl Engine {
 				rfc2822_from_seconds(info.timestamp),
 				info.size,
 				info.num_files,
-			)
-			.expect("should be able to write to string buffer");
+			)?;
 		}
 
 		Ok(res)
@@ -226,16 +223,16 @@ impl Engine {
 			Err(e) => Ok(String::from(e)),
 			Ok(files) => {
 				let mut res = String::new();
-				writeln!(res, "| lev  | sst  | keys | dels | size | column |").expect("written to string buffer");
-				writeln!(res, "| ---: | :--- | ---: | ---: | ---: | :---   |").expect("written to string buffer");
+				writeln!(res, "| lev  | sst  | keys | dels | size | column |")?;
+				writeln!(res, "| ---: | :--- | ---: | ---: | ---: | :---   |")?;
 				for file in files {
 					writeln!(
 						res,
 						"| {} | {:<13} | {:7}+ | {:4}- | {:9} | {} |",
 						file.level, file.name, file.num_entries, file.num_deletions, file.size, file.column_family_name,
-					)
-					.expect("should be able to writeln to string buffer");
+					)?;
 				}
+
 				Ok(res)
 			},
 		}