diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 2cd7d6498b0..24ffeecda11 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,3 +1,8 @@
+2018-07-30  Tom Tromey  <tom@tromey.com>
+
+	* nat/linux-osdata.c (pid_pgid_entry::operator<): Fix
+	irreflexivity violation.
+
 2018-07-30  Tom Tromey  <tom@tromey.com>
 
 	* cli/cli-decode.c (lookup_cmd): Remove lint code.
diff --git a/gdb/nat/linux-osdata.c b/gdb/nat/linux-osdata.c
index 25e895df190..2323dcc878b 100644
--- a/gdb/nat/linux-osdata.c
+++ b/gdb/nat/linux-osdata.c
@@ -415,9 +415,11 @@ struct pid_pgid_entry
 
     /* Process group leaders always come first...  */
     if (this->is_leader ())
-      return true;
-
-    if (other.is_leader ())
+      {
+	if (!other.is_leader ())
+	  return true;
+      }
+    else if (other.is_leader ())
       return false;
 
     /* ...else sort by PID.  */