diff --git a/src/libfetchers/git.cc b/src/libfetchers/git.cc
index f8d89ab2fcd..a4fd6975c13 100644
--- a/src/libfetchers/git.cc
+++ b/src/libfetchers/git.cc
@@ -529,7 +529,13 @@ struct GitInputScheme : InputScheme
             if (input.getRev()) {
                 try {
                     runProgram("git", true, { "-C", repoDir, "--git-dir", gitDir, "cat-file", "-e", input.getRev()->gitRev() });
-                    doFetch = false;
+                    auto res = runProgram("git", true, { "-C", repoDir, "--git-dir", gitDir, "for-each-ref", fmt("--contains=%s", input.getRev()->gitRev()) });
+                    if ( res == "" ) {
+                        printTalkative("Rev %s was not associated with any ref (possibly due to an incomplete fetch) - performing a fetch", input.getRev()->gitRev(), actualUrl);
+                        doFetch = true;
+                    } else {
+                        doFetch = false;
+		    }
                 } catch (ExecError & e) {
                     if (WIFEXITED(e.status)) {
                         doFetch = true;
@@ -630,7 +636,7 @@ struct GitInputScheme : InputScheme
                 // everything to ensure we get the rev.
                 Activity act(*logger, lvlTalkative, actUnknown, fmt("making temporary clone of '%s'", repoDir));
                 runProgram("git", true, { "-C", tmpDir, "fetch", "--quiet", "--force",
-                        "--update-head-ok", "--", repoDir, "refs/*:refs/*" }, {}, true);
+                        "--update-head-ok", "--", repoDir, "refs/*:refs/*", input.getRev()->gitRev() }, {}, true);
             }
 
             runProgram("git", true, { "-C", tmpDir, "checkout", "--quiet", input.getRev()->gitRev() });