run.go                      | 13 +++++++++++++
 t/goredo-$1-touch.t         |  3 ++-
 t/goredo-already-existing.t | 24 ++++++++++++++++++++++++

diff --git a/run.go b/run.go
index 76555e150c48d1e4952c59369c572cfbcd6b1de60b6d875088daf23eaa63d732..2a714e065242e578f60d4963f11797dda456e9f3be16de6ccb05b7cf0a434996 100644
--- a/run.go
+++ b/run.go
@@ -298,6 +298,19 @@ 			Jobs.Done()
 		}()
 		return nil
 	}
+	if inodePrev == nil && FileExists(tgt.a) {
+		lockRelease()
+		if StopIfMod {
+			return fmt.Errorf("%s already existing", tgt)
+		}
+		Jobs.Add(1)
+		tracef(CWarn, "%s already existing: not redoing", tgt)
+		go func() {
+			errs <- nil
+			Jobs.Done()
+		}()
+		return nil
+	}
 	dep = nil
 
 	// Start preparing .dep
diff --git a/t/goredo-$1-touch.t b/t/goredo-$1-touch.t
index c44dcf703b97ec84ea2dc9f1dcc62085351386dc44823b28bcfdd51d2e2e6e6f..a2bdb68fe4d8be2783ab9a707a27914336a014507d30de5b60f9c7cf883965d1 100755
--- a/t/goredo-$1-touch.t
+++ b/t/goredo-$1-touch.t
@@ -5,6 +5,7 @@ . $SHARNESS_TEST_SRCDIR/sharness.sh
 export REDO_TOP_DIR="`pwd`" REDO_NO_PROGRESS=1
 
 echo touch \$1 >foo.do
-test_expect_success "it fails" 'redo foo ; [ $? = 1 ]'
+test_expect_success "it fails" 'redo foo 2>out ; [ $? = 1 ]'
+test_expect_success "message" 'grep -q "touched" out'
 
 test_done
diff --git a/t/goredo-already-existing.t b/t/goredo-already-existing.t
new file mode 100755
index 0000000000000000000000000000000000000000..fb358f6c51cd8b4bde8eb6c0adfe32a7de136ca4127a34c0acd51bbf19b5281c
--- /dev/null
+++ b/t/goredo-already-existing.t
@@ -0,0 +1,24 @@
+#!/bin/sh
+
+test_description="Check failing if \$1 already exists"
+. $SHARNESS_TEST_SRCDIR/sharness.sh
+export REDO_TOP_DIR="`pwd`" REDO_NO_PROGRESS=1
+
+echo echo ok >foo.do
+touch foo
+test_expect_success "does not fail" "redo foo 2>out"
+test_expect_success "message" 'grep -q "already existing" out'
+
+export REDO_STOP_IF_MODIFIED=1
+test_expect_success "must fail" 'redo foo 2>out ; [ $? = 1 ]'
+unset REDO_STOP_IF_MODIFIED
+test_expect_success "message" 'grep -q "already existing" out'
+
+rm foo
+test_expect_success "ok" "redo foo"
+
+echo overwrite >foo
+test_expect_success "externally modified" "redo foo 2>out"
+test_expect_success "message" 'grep -q "externally modified" out'
+
+test_done