diff --git a/src/lib/sds_extras.c b/src/lib/sds_extras.c
index 4c0c779fb..0ab830471 100644
--- a/src/lib/sds_extras.c
+++ b/src/lib/sds_extras.c
@@ -320,8 +320,9 @@ sds sds_catjsonchar(sds s, const char c) {
  */
 sds sds_catchar(sds s, const char c) {
     // Make sure there is always space for at least 1 char.
-    if (sdsavail(s) == 0) {
-        s = sdsMakeRoomFor(s, 1);
+    s = sdsMakeRoomFor(s, 1);
+    if (s == NULL) {
+        return NULL;
     }
     size_t i = sdslen(s);
     s[i++] = c;
diff --git a/test/tests/test_sds_extras.c b/test/tests/test_sds_extras.c
index 1679f4b8e..408935ae8 100644
--- a/test/tests/test_sds_extras.c
+++ b/test/tests/test_sds_extras.c
@@ -142,6 +142,12 @@ UTEST(sds_extras, test_sds_catchar) {
     s = sds_catchar(s, 'a');
     ASSERT_STREQ("a", s);
     ASSERT_EQ(strlen(s), sdslen(s));
+
+    s = sdscat(s, "bcdefghijklmnopqrstuvwxy");
+    s = sds_catchar(s, 'z');
+    ASSERT_STREQ("abcdefghijklmnopqrstuvwxyz", s);
+    ASSERT_EQ(strlen(s), sdslen(s));
+
     sdsfree(s);
 }