4 files changed, 8 insertions, 6 deletions
diff --git a/libbuild2/adhoc-rule-buildscript.cxx b/libbuild2/adhoc-rule-buildscript.cxx
index e8bc20d..b981b8d 100644
--- a/libbuild2/adhoc-rule-buildscript.cxx
+++ b/libbuild2/adhoc-rule-buildscript.cxx
@@ -505,7 +505,7 @@ namespace build2
     if (update && dd.reading () && !ctx.dry_run)
       dd.touch = timestamp_unknown;
 
-    dd.close ();
+    dd.close (false /* mtime_check */);
     md->dd = move (dd.path);
 
     // Pass on base scope and update/mtime.
diff --git a/libbuild2/cc/compile-rule.cxx b/libbuild2/cc/compile-rule.cxx
index 3c77ad3..db9e6cb 100644
--- a/libbuild2/cc/compile-rule.cxx
+++ b/libbuild2/cc/compile-rule.cxx
@@ -1424,7 +1424,7 @@ namespace build2
         if (u && dd.reading () && !ctx.dry_run)
           dd.touch = timestamp_unknown;
 
-        dd.close ();
+        dd.close (false /* mtime_check */);
         md.dd = move (dd.path);
 
         // If the preprocessed output is suitable for compilation, then pass
diff --git a/libbuild2/depdb.cxx b/libbuild2/depdb.cxx
index 1215e78..e50870c 100644
--- a/libbuild2/depdb.cxx
+++ b/libbuild2/depdb.cxx
@@ -281,7 +281,7 @@ namespace build2
   }
 
   void depdb::
-  close ()
+  close (bool mc)
   {
     // If we are at eof, then it means all lines are good, there is the "end
     // marker" at the end, and we don't need to do anything, except, maybe
@@ -329,7 +329,7 @@ namespace build2
       change (true /* truncate */);
     }
 
-    if (mtime_check ())
+    if (mc && mtime_check ())
       start_ = system_clock::now ();
 
     if (state_ == state::write)
diff --git a/libbuild2/depdb.hxx b/libbuild2/depdb.hxx
index 9cff281..5b5052d 100644
--- a/libbuild2/depdb.hxx
+++ b/libbuild2/depdb.hxx
@@ -118,10 +118,12 @@ namespace build2
     // function will "chop off" lines that haven't been read.
     //
     // Make sure to also call check_mtime() after updating the target to
-    // perform the target/database modification times sanity checks.
+    // perform the target/database modification times sanity checks. Pass
+    // false to close() to avoid unnecessary work if using the static version
+    // of check_mtime() (or not using it at all for some reason).
     //
     void
-    close ();
+    close (bool mtime_check = true);
 
     // Flush any unwritten data to disk. This is primarily useful when reusing
     // a (partially written) database as an input to external programs (e.g.,