diff --git a/src/t_set.c b/src/t_set.c
index 7522a68cf..f679676c2 100644
--- a/src/t_set.c
+++ b/src/t_set.c
@@ -1859,8 +1859,7 @@ void sunionCommand(client *c) {
 void sunioncardCommand(client *c) {
     long j;
     long numkeys = 0;
-    long limit = 0;
-    int have_limit = 0;
+    long limit = 0; /* 0 means no limit. */
     int approx = 0;
 
     if (getRangeLongFromObjectOrReply(c, c->argv[1], 1, LONG_MAX,
@@ -1880,7 +1879,6 @@ void sunioncardCommand(client *c) {
             if (getPositiveLongFromObjectOrReply(c, c->argv[j], &limit,
                                                  "LIMIT can't be negative") != C_OK)
                 return;
-            have_limit = 1;
         } else if (!strcasecmp(opt, "APPROX")) {
             approx = 1;
         } else {
@@ -1889,11 +1887,6 @@ void sunioncardCommand(client *c) {
         }
     }
 
-    if (have_limit && limit == 0) {
-        addReplyLongLong(c, 0);
-        return;
-    }
-
     if (approx) {
         /* HLL-based approximate cardinality: use a temporary HLL object
          * with the standard sparse→dense encoding (same as PFADD). */
@@ -1938,7 +1931,7 @@ void sunioncardCommand(client *c) {
                 }
 
                 elements_processed++;
-                if (have_limit &&
+                if (limit > 0 &&
                     (elements_processed % HLL_APPROX_CHECK_INTERVAL == 0)) {
                     uint64_t est = hllCount(hllobj->ptr, NULL);
                     if (est >= (uint64_t)limit) {
@@ -1951,7 +1944,7 @@ void sunioncardCommand(client *c) {
         }
 
         uint64_t cardinality = hllCount(hllobj->ptr, NULL);
-        if (have_limit && cardinality > (uint64_t)limit)
+        if (limit > 0 && cardinality > (uint64_t)limit)
             cardinality = (uint64_t)limit;
 
         if (server.memory_tracking_enabled) {
diff --git a/tests/unit/type/set.tcl b/tests/unit/type/set.tcl
index 8480757da..ba92800b8 100644
--- a/tests/unit/type/set.tcl
+++ b/tests/unit/type/set.tcl
@@ -306,11 +306,11 @@ foreach type {single multiple single_multiple} {
         assert_equal $exact $approx
     }
 
-    test "SUNIONCARD LIMIT 0 returns 0 immediately" {
+    test "SUNIONCARD LIMIT 0 means no limit" {
         r del set1{t} set2{t}
         r sadd set1{t} a b c
         r sadd set2{t} c d e
-        assert_equal 0 [r sunioncard 2 set1{t} set2{t} LIMIT 0]
+        assert_equal 5 [r sunioncard 2 set1{t} set2{t} LIMIT 0]
     }
 
     test "SUNIONCARD with both APPROX and LIMIT" {
@@ -318,7 +318,7 @@ foreach type {single multiple single_multiple} {
         r sadd set1{t} a b c
         r sadd set2{t} c d e
         assert_equal 3 [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 3]
-        assert_equal 0 [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 0]
+        assert_equal 5 [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 0]
     }
 
     test "SUNIONCARD APPROX with large sets is within HLL error margin" {
@@ -421,7 +421,7 @@ foreach type {single multiple single_multiple} {
         test "SUNIONCARD with two sets - $type" {
             set expected [llength [lsort -uniq "[r smembers set1{t}] [r smembers set2{t}]"]]
             assert_equal $expected [r sunioncard 2 set1{t} set2{t}]
-            assert_equal 0 [r sunioncard 2 set1{t} set2{t} LIMIT 0]
+            assert_equal $expected [r sunioncard 2 set1{t} set2{t} LIMIT 0]
             assert_equal 3 [r sunioncard 2 set1{t} set2{t} LIMIT 3]
             assert_equal $expected [r sunioncard 2 set1{t} set2{t} LIMIT 10000]
         }
@@ -429,7 +429,7 @@ foreach type {single multiple single_multiple} {
         test "SUNIONCARD against three sets - $type" {
             set expected [llength [lsort -uniq "[r smembers set1{t}] [r smembers set2{t}] [r smembers set3{t}]"]]
             assert_equal $expected [r sunioncard 3 set1{t} set2{t} set3{t}]
-            assert_equal 0 [r sunioncard 3 set1{t} set2{t} set3{t} LIMIT 0]
+            assert_equal $expected [r sunioncard 3 set1{t} set2{t} set3{t} LIMIT 0]
             assert_equal 2 [r sunioncard 3 set1{t} set2{t} set3{t} LIMIT 2]
             assert_equal $expected [r sunioncard 3 set1{t} set2{t} set3{t} LIMIT 10000]
         }
@@ -447,7 +447,8 @@ foreach type {single multiple single_multiple} {
         }
 
         test "SUNIONCARD APPROX with LIMIT - $type" {
-            assert_equal 0 [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 0]
+            set approx_no_limit [r sunioncard 2 set1{t} set2{t} APPROX]
+            assert_equal $approx_no_limit [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 0]
             assert_equal 10 [r sunioncard 2 set1{t} set2{t} APPROX LIMIT 10]
         }