diff --git a/builtin-rev-list.c b/builtin-rev-list.c
index 414b2f32b2..33726b8d84 100644
--- a/builtin-rev-list.c
+++ b/builtin-rev-list.c
@@ -84,7 +84,8 @@ static void show_commit(struct commit *commit)
 		strbuf_init(&buf, 0);
 		pretty_print_commit(revs.commit_format, commit,
 					&buf, revs.abbrev, NULL, NULL, revs.date_mode);
-		printf("%s%c", buf.buf, hdr_termination);
+		if (buf.len)
+			printf("%s%c", buf.buf, hdr_termination);
 		strbuf_release(&buf);
 	}
 	maybe_flush_or_die(stdout, "stdout");
diff --git a/commit.c b/commit.c
index 62cc74d7a9..20fb2209cb 100644
--- a/commit.c
+++ b/commit.c
@@ -876,9 +876,6 @@ void format_commit_message(const struct commit *commit,
 	}
 	if (msg[i])
 		table[IBODY].value = xstrdup(msg + i);
-	for (i = 0; i < ARRAY_SIZE(table); i++)
-		if (!table[i].value)
-			interp_set_entry(table, i, "<unknown>");
 
 	len = interpolate(sb->buf + sb->len, strbuf_avail(sb),
 				format, table, ARRAY_SIZE(table));
diff --git a/interpolate.c b/interpolate.c
index 3de583238d..6ef53f2465 100644
--- a/interpolate.c
+++ b/interpolate.c
@@ -73,8 +73,12 @@ unsigned long interpolate(char *result, unsigned long reslen,
 			/* Check for valid interpolation. */
 			if (i < ninterps) {
 				value = interps[i].value;
-				valuelen = strlen(value);
+				if (!value) {
+					src += namelen;
+					continue;
+				}
 
+				valuelen = strlen(value);
 				if (newlen + valuelen < reslen) {
 					/* Substitute. */
 					memcpy(dest, value, valuelen);
diff --git a/log-tree.c b/log-tree.c
index 3e5e6acfaf..23191543d5 100644
--- a/log-tree.c
+++ b/log-tree.c
@@ -280,7 +280,8 @@ void show_log(struct rev_info *opt, const char *sep)
 	if (opt->show_log_size)
 		printf("log size %i\n", (int)msgbuf.len);
 
-	printf("%s%s%s", msgbuf.buf, extra, sep);
+	if (msgbuf.len)
+		printf("%s%s%s", msgbuf.buf, extra, sep);
 	strbuf_release(&msgbuf);
 }
 
diff --git a/t/t6006-rev-list-format.sh b/t/t6006-rev-list-format.sh
index ad6d0b8c9d..1e4541afea 100755
--- a/t/t6006-rev-list-format.sh
+++ b/t/t6006-rev-list-format.sh
@@ -79,9 +79,7 @@ EOF
 
 test_format encoding %e <<'EOF'
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format subject %s <<'EOF'
@@ -93,9 +91,7 @@ EOF
 
 test_format body %b <<'EOF'
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format colors %Credfoo%Cgreenbar%Cbluebaz%Cresetxyzzy <<'EOF'
@@ -121,9 +117,7 @@ test_format complex-encoding %e <<'EOF'
 commit f58db70b055c5718631e5c61528b28b12090cdea
 iso8859-1
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_format complex-subject %s <<'EOF'
@@ -142,9 +136,7 @@ and it will be encoded in iso8859-1. We should therefore
 include an iso8859 character: ¡bueno!
 
 commit 131a310eb913d107dd3c09a65d1651175898735d
-<unknown>
 commit 86c75cfd708a0e5868dc876ed5b8bb66c80b4873
-<unknown>
 EOF
 
 test_done
diff --git a/t/t7500-commit.sh b/t/t7500-commit.sh
index f11ada8617..abbf54ba63 100755
--- a/t/t7500-commit.sh
+++ b/t/t7500-commit.sh
@@ -81,7 +81,7 @@ test_expect_success 'explicit commit message should override template' '
 	git add foo &&
 	GIT_EDITOR=../t7500/add-content git commit --template "$TEMPLATE" \
 		-m "command line msg" &&
-	commit_msg_is "command line msg<unknown>"
+	commit_msg_is "command line msg"
 '
 
 test_expect_success 'commit message from file should override template' '
@@ -90,7 +90,7 @@ test_expect_success 'commit message from file should override template' '
 	echo "standard input msg" |
 		GIT_EDITOR=../t7500/add-content git commit \
 			--template "$TEMPLATE" --file - &&
-	commit_msg_is "standard input msg<unknown>"
+	commit_msg_is "standard input msg"
 '
 
 test_done