diff --git a/crates/ra_prof/src/memory_usage.rs b/crates/ra_prof/src/memory_usage.rs
index 857b513212..22b61e4a28 100644
--- a/crates/ra_prof/src/memory_usage.rs
+++ b/crates/ra_prof/src/memory_usage.rs
@@ -3,35 +3,43 @@ use std::fmt;
 
 use cfg_if::cfg_if;
 
+#[derive(Copy, Clone)]
 pub struct MemoryUsage {
     pub allocated: Bytes,
 }
 
-impl MemoryUsage {
-    pub fn current() -> MemoryUsage {
-        cfg_if! {
-            if #[cfg(target_os = "linux")] {
-                // Note: This is incredibly slow.
-                let alloc = unsafe { libc::mallinfo() }.uordblks as u32 as usize;
-                MemoryUsage { allocated: Bytes(alloc) }
-            } else {
-                MemoryUsage { allocated: Bytes(0) }
-            }
-        }
-    }
-}
-
 impl fmt::Display for MemoryUsage {
     fn fmt(&self, fmt: &mut fmt::Formatter) -> fmt::Result {
         write!(fmt, "{}", self.allocated)
     }
 }
 
+impl std::ops::Sub for MemoryUsage {
+    type Output = MemoryUsage;
+    fn sub(self, rhs: MemoryUsage) -> MemoryUsage {
+        MemoryUsage { allocated: self.allocated - rhs.allocated }
+    }
+}
+
+impl MemoryUsage {
+    pub fn current() -> MemoryUsage {
+        cfg_if! {
+            if #[cfg(target_os = "linux")] {
+                // Note: This is incredibly slow.
+                let alloc = unsafe { libc::mallinfo() }.uordblks as u32 as isize;
+                MemoryUsage { allocated: Bytes(alloc) }
+            } else {
+                MemoryUsage { allocated: Bytes(0) }
+            }
+        }
+    }
+}
+
 #[derive(Default, PartialEq, Eq, PartialOrd, Ord, Hash, Clone, Copy)]
-pub struct Bytes(usize);
+pub struct Bytes(isize);
 
 impl Bytes {
-    pub fn megabytes(self) -> usize {
+    pub fn megabytes(self) -> isize {
         self.0 / 1024 / 1024
     }
 }
@@ -41,10 +49,10 @@ impl fmt::Display for Bytes {
         let bytes = self.0;
         let mut value = bytes;
         let mut suffix = "b";
-        if value > 4096 {
+        if value.abs() > 4096 {
             value /= 1024;
             suffix = "kb";
-            if value > 4096 {
+            if value.abs() > 4096 {
                 value /= 1024;
                 suffix = "mb";
             }
@@ -55,7 +63,7 @@ impl fmt::Display for Bytes {
 
 impl std::ops::AddAssign<usize> for Bytes {
     fn add_assign(&mut self, x: usize) {
-        self.0 += x;
+        self.0 += x as isize;
     }
 }
 
diff --git a/crates/rust-analyzer/src/cli/analysis_stats.rs b/crates/rust-analyzer/src/cli/analysis_stats.rs
index 66d201ba66..cf0d82b62c 100644
--- a/crates/rust-analyzer/src/cli/analysis_stats.rs
+++ b/crates/rust-analyzer/src/cli/analysis_stats.rs
@@ -111,11 +111,7 @@ pub fn analysis_stats(
     eprintln!("Total declarations: {}", num_decls);
     eprintln!("Total functions: {}", funcs.len());
     let item_collection_memory = ra_prof::memory_usage();
-    eprintln!(
-        "Item Collection: {:?}, {}",
-        analysis_time.elapsed(),
-        item_collection_memory.allocated
-    );
+    eprintln!("Item Collection: {:?}, {}", analysis_time.elapsed(), item_collection_memory);
 
     if randomize {
         shuffle(&mut rng, &mut funcs);
@@ -140,7 +136,7 @@ pub fn analysis_stats(
         eprintln!(
             "Parallel Inference: {:?}, {}",
             inference_time.elapsed(),
-            ra_prof::memory_usage().allocated
+            ra_prof::memory_usage()
         );
     }
 
@@ -297,11 +293,7 @@ pub fn analysis_stats(
 
     let inference_time = inference_time.elapsed();
     let total_memory = ra_prof::memory_usage();
-    eprintln!(
-        "Inference: {:?}, {}",
-        inference_time,
-        total_memory.allocated - item_collection_memory.allocated
-    );
+    eprintln!("Inference: {:?}, {}", inference_time, total_memory - item_collection_memory);
 
     let analysis_time = analysis_time.elapsed();
     eprintln!("Total: {:?}, {}", analysis_time, total_memory);