diff --git a/src/util.rs b/src/util.rs
index d4702e5..34c07c8 100644
--- a/src/util.rs
+++ b/src/util.rs
@@ -307,14 +307,16 @@ pub fn editor_cmd() -> impl Iterator<Item = impl AsRef<OsStr>> + Clone {
             .arg("core.editor")
             .output()
         {
-            let mut output = output.stdout;
-            // the last byte should be a nul
-            assert_eq!(Some(0), output.pop());
-
-            if !output.is_empty() {
-                let cmd = split_whitespace(&output);
-                if !cmd.is_empty() {
-                    return cmd;
+            if output.status.success() {
+                let mut output = output.stdout;
+                // the last byte should be a nul
+                assert!(matches!(output.pop(), Some(0) | None));
+
+                if !output.is_empty() {
+                    let cmd = split_whitespace(&output);
+                    if !cmd.is_empty() {
+                        return cmd;
+                    }
                 }
             }
         }