diff --git a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
index 1fe8d0ce4209..051871020af7 100644
--- a/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
+++ b/src/tools/rust-analyzer/crates/rust-analyzer/src/config.rs
@@ -573,8 +573,7 @@ config_data! {
         /// List of cfg options to enable with the given values.
         cargo_cfgs: Vec<String> = {
             vec!["debug_assertion".into(), "miri".into()]
-        }
-        ,
+        },
         /// Extra arguments that are passed to every cargo invocation.
         cargo_extraArgs: Vec<String> = vec![],
         /// Extra environment variables that will be set when running cargo, rustc
@@ -1942,17 +1941,13 @@ impl Config {
                 global: CfgDiff::new(
                     self.cargo_cfgs(source_root)
                         .iter()
-                        // parse any cfg setting formatted as key=value
-                        .map(|s| {
+                        // parse any cfg setting formatted as key=value or just key (without value)
+                        .filter_map(|s| {
                             let mut sp = s.splitn(2, "=");
                             let key = sp.next();
                             let val = sp.next();
-                            (key, val)
+                            key.map(|key| (key, val))
                         })
-                        // we filter out anything with a None key
-                        .filter(|(key, _)| key.is_some())
-                        // unwrap cannot panic here as we are sure key is Some
-                        .map(|(key, val)| (key.unwrap(), val))
                         .map(|(key, val)| match val {
                             Some(val) => CfgAtom::KeyValue {
                                 key: Symbol::intern(key),