diff --git a/src/engine/sim_engine/pool.rs b/src/engine/sim_engine/pool.rs
index d5e127006f..71e9dc6953 100644
--- a/src/engine/sim_engine/pool.rs
+++ b/src/engine/sim_engine/pool.rs
@@ -760,17 +760,20 @@ impl Pool for SimPool {
     }
 
     fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
-        self.filesystems
-            .iter()
-            .filter_map(|(name, uuid, fs)| {
-                if fs_name.map(|n| *n == **name).unwrap_or(true) {
-                    Some(serde_json::to_string(&fs.record(name, *uuid)).map_err(|e| e.into()))
-                } else {
-                    None
-                }
-            })
-            .collect::<StratisResult<Vec<_>>>()
-            .map(|v| v.join("\n"))
+        serde_json::to_string(
+            &self
+                .filesystems
+                .iter()
+                .filter_map(|(name, uuid, fs)| {
+                    if fs_name.map(|n| *n == **name).unwrap_or(true) {
+                        Some((uuid, fs.record(name, *uuid)))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
     }
 
     fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
diff --git a/src/engine/strat_engine/thinpool/thinpool.rs b/src/engine/strat_engine/thinpool/thinpool.rs
index 4f14595ad0..97ea5d79df 100644
--- a/src/engine/strat_engine/thinpool/thinpool.rs
+++ b/src/engine/strat_engine/thinpool/thinpool.rs
@@ -731,33 +731,39 @@ impl<B> ThinPool<B> {
 
     /// Calculate filesystem metadata from current state
     pub fn current_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
-        self.filesystems
-            .iter()
-            .filter_map(|(name, uuid, fs)| {
-                if fs_name.map(|n| *n == **name).unwrap_or(true) {
-                    Some(serde_json::to_string(&fs.record(name, *uuid)).map_err(|e| e.into()))
-                } else {
-                    None
-                }
-            })
-            .collect::<StratisResult<Vec<_>>>()
-            .map(|v| v.join("\n"))
+        serde_json::to_string(
+            &self
+                .filesystems
+                .iter()
+                .filter_map(|(name, uuid, fs)| {
+                    if fs_name.map(|n| *n == **name).unwrap_or(true) {
+                        Some((*uuid, fs.record(name, *uuid)))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
     }
 
     /// Read filesystem metadata from mdv
     pub fn last_fs_metadata(&self, fs_name: Option<&str>) -> StratisResult<String> {
-        self.mdv
-            .filesystems()?
-            .iter()
-            .filter_map(|fssave| {
-                if fs_name.map(|n| *n == fssave.name).unwrap_or(true) {
-                    Some(serde_json::to_string(fssave).map_err(|e| e.into()))
-                } else {
-                    None
-                }
-            })
-            .collect::<StratisResult<Vec<_>>>()
-            .map(|v| v.join("\n"))
+        serde_json::to_string(
+            &self
+                .mdv
+                .filesystems()?
+                .iter()
+                .filter_map(|fssave| {
+                    if fs_name.map(|n| *n == fssave.name).unwrap_or(true) {
+                        Some((fssave.uuid, fssave))
+                    } else {
+                        None
+                    }
+                })
+                .collect::<HashMap<_, _>>(),
+        )
+        .map_err(|e| e.into())
     }
 }