diff --git a/src/libstore/build.cc b/src/libstore/build.cc
index b682a80195fb5ad5549fb793e19d76c79056e2b7..b61ea5298e1e6028cf27683b87cf2bc889bfb4c9 100644
--- a/src/libstore/build.cc
+++ b/src/libstore/build.cc
@@ -3791,7 +3791,7 @@ void LocalStore::buildPaths(const PathSet & drvPaths, BuildMode buildMode)
         }
 
     if (!failed.empty())
-        throw Error(worker.exitStatus(), "build of %s failed",showPaths(failed));
+        throw Error(worker.exitStatus(), "build of %s failed", showPaths(failed));
 }