diff --git a/builtin/log.c b/builtin/log.c
index 09cf43e6d40..e7b7db1cacf 100644
--- a/builtin/log.c
+++ b/builtin/log.c
@@ -351,7 +351,8 @@ static int git_log_config(const char *var, const char *value, void *cb)
 	}
 	if (!prefixcmp(var, "color.decorate."))
 		return parse_decorate_color_config(var, 15, value);
-
+	if (grep_config(var, value, cb) < 0)
+		return -1;
 	return git_diff_ui_config(var, value, cb);
 }
 
@@ -360,6 +361,7 @@ int cmd_whatchanged(int argc, const char **argv, const char *prefix)
 	struct rev_info rev;
 	struct setup_revision_opt opt;
 
+	init_grep_defaults();
 	git_config(git_log_config, NULL);
 
 	init_revisions(&rev, prefix);
@@ -450,6 +452,7 @@ int cmd_show(int argc, const char **argv, const char *prefix)
 	struct pathspec match_all;
 	int i, count, ret = 0;
 
+	init_grep_defaults();
 	git_config(git_log_config, NULL);
 
 	init_pathspec(&match_all, NULL);
@@ -530,6 +533,7 @@ int cmd_log_reflog(int argc, const char **argv, const char *prefix)
 	struct rev_info rev;
 	struct setup_revision_opt opt;
 
+	init_grep_defaults();
 	git_config(git_log_config, NULL);
 
 	init_revisions(&rev, prefix);
@@ -552,6 +556,7 @@ int cmd_log(int argc, const char **argv, const char *prefix)
 	struct rev_info rev;
 	struct setup_revision_opt opt;
 
+	init_grep_defaults();
 	git_config(git_log_config, NULL);
 
 	init_revisions(&rev, prefix);
@@ -1121,6 +1126,7 @@ int cmd_format_patch(int argc, const char **argv, const char *prefix)
 	extra_hdr.strdup_strings = 1;
 	extra_to.strdup_strings = 1;
 	extra_cc.strdup_strings = 1;
+	init_grep_defaults();
 	git_config(git_format_config, NULL);
 	init_revisions(&rev, prefix);
 	rev.commit_format = CMIT_FMT_EMAIL;