diff --git a/builtin/log.c b/builtin/log.c
index a70fba198f..eaf511aab8 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -1085,6 +1085,15 @@ static int git_format_config(const char *var, const char *value, void *cb)
 		return 0;
 	}
 
+	/*
+	 * ignore some porcelain config which would otherwise be parsed by
+	 * git_diff_ui_config(), via git_log_config(); we can't just avoid
+	 * diff_ui_config completely, because we do care about some ui options
+	 * like color.
+	 */
+	if (!strcmp(var, "diff.noprefix"))
+		return 0;
+
 	return git_log_config(var, value, cb);
 }
 
diff --git a/t/t4014-format-patch.sh b/t/t4014-format-patch.sh
index f3313b8c58..f5a41fd47e 100755
--- a/t/t4014-format-patch.sh
+++ b/t/t4014-format-patch.sh
@@ -2386,4 +2386,9 @@ test_expect_success 'interdiff: solo-patch' '
 	test_cmp expect actual
 '
 
+test_expect_success 'format-patch does not respect diff.noprefix' '
+	git -c diff.noprefix format-patch -1 --stdout >actual &&
+	grep "^--- a/blorp" actual
+'
+
 test_done