diff --git a/src/libstore/local-store.cc b/src/libstore/local-store.cc
index 64b5dd961..7f7f70bb8 100644
--- a/src/libstore/local-store.cc
+++ b/src/libstore/local-store.cc
@@ -49,10 +49,14 @@ static void throwSQLiteError(sqlite3 * db, const format & f)
 {
     int err = sqlite3_errcode(db);
     if (err == SQLITE_BUSY || err == SQLITE_PROTOCOL) {
-        static bool warned = false;
-        if (!warned) {
-            printMsg(lvlError, "warning: SQLite database is busy");
-            warned = true;
+        if (err == SQLITE_PROTOCOL)
+            printMsg(lvlError, "warning: SQLite database is busy (SQLITE_PROTOCOL)");
+        else {
+            static bool warned = false;
+            if (!warned) {
+                printMsg(lvlError, "warning: SQLite database is busy");
+                warned = true;
+            }
         }
         /* Sleep for a while since retrying the transaction right away
            is likely to fail again. */