diff --git a/libcockatrice_filters/libcockatrice/filters/filter_string.cpp b/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
index aaf391c03..f08004856 100644
--- a/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
+++ b/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
@@ -65,7 +65,7 @@ RegexMatcherString <- ('\\/' / !'/' .)+
 FlexStringValue <- CompactStringSet / String / [(] StringList [)]
 CompactStringSet <- StringListString ([,+] StringListString)+
 
-SetExpression <- NumericOperator ws? String
+SetExpression <- <NumericOperator> ws? String
 
 NumericExpression <- NumericOperator ws? NumericValue
 NumericOperator <- [=:] / <[><!][=]?>
@@ -114,16 +114,8 @@ static void setupParserRules()
             };
         }
 
-        auto matcher = std::any_cast<NumberMatcher>(sv[0]);
-        return [=](const CardData &x) -> bool {
-            const auto &sets = x->getSets().values();
-            auto matchesSet = [&](const PrintingInfo &printing) {
-                return printing.getSet()->getEnabled() && matcher(printing.getSet()->getReleaseDate().toJulianDay());
-            };
-            return std::any_of(sets.begin(), sets.end(), [&](const auto &printings) {
-                return std::any_of(printings.begin(), printings.end(), matchesSet);
-            });
-        };
+        auto matcher = std::any_cast<Filter>(sv[0]);
+        return matcher;
     };
     search["Rarity"] = [](const peg::SemanticValues &sv) -> QString {
         switch (tolower(std::string(sv.sv())[0])) {
@@ -300,17 +292,57 @@ static void setupParserRules()
         return [=](int s) { return comparer(s, arg); };
     };
 
-    search["SetExpression"] = [](const peg::SemanticValues &sv) -> NumberMatcher {
+    search["SetExpression"] = [](const peg::SemanticValues &sv) -> Filter {
         const auto comparer = std::any_cast<NumberComparer>(sv[0]);
         const auto setCode = std::any_cast<QString>(sv[1]);
+        const auto operatorText = QString::fromStdString(std::string(sv.token(0)));
+
+        auto printingsOf = [](const CardData &x) {
+            QList<PrintingInfo> printings;
+            for (const auto &printingsPerSet : x->getSets()) {
+                printings.append(printingsPerSet);
+            }
+            return printings;
+        };
+        auto isExactSet = [setCode](const PrintingInfo &printing) {
+            return printing.getSet()->getEnabled() &&
+                   printing.getSet()->getShortName().compare(setCode, Qt::CaseInsensitive) == 0;
+        };
+
+        if (operatorText == ":" || operatorText == "=") {
+            return [=](const CardData &x) {
+                const auto printings = printingsOf(x);
+                return std::any_of(printings.begin(), printings.end(), isExactSet);
+            };
+        }
+        if (operatorText == "!" || operatorText == "!=") {
+            return [=](const CardData &x) {
+                const auto printings = printingsOf(x);
+                return std::none_of(printings.begin(), printings.end(), isExactSet);
+            };
+        }
+
         const auto allSets = CardDatabaseManager::getInstance()->getSetList();
-        for (auto &set : allSets) {
-            if (set->getShortName() == setCode) {
-                const int releaseDate = set->getReleaseDate().toJulianDay();
-                return [=](int s) { return comparer(s, releaseDate); };
+        int releaseDate = 0;
+        bool setFound = false;
+        for (const auto &set : allSets) {
+            if (set->getShortName().compare(setCode, Qt::CaseInsensitive) == 0) {
+                releaseDate = set->getReleaseDate().toJulianDay();
+                setFound = true;
+                break;
             }
         }
-        return [](int) { return false; };
+        if (!setFound) {
+            return [](const CardData &) { return false; };
+        }
+        auto matchesReleaseDate = [comparer, releaseDate](const PrintingInfo &printing) {
+            return printing.getSet()->getEnabled() &&
+                   comparer(printing.getSet()->getReleaseDate().toJulianDay(), releaseDate);
+        };
+        return [=](const CardData &x) {
+            const auto printings = printingsOf(x);
+            return std::any_of(printings.begin(), printings.end(), matchesReleaseDate);
+        };
     };
 
     search["NormalMatcher"] = [](const peg::SemanticValues &sv) -> StringMatcher {
diff --git a/tests/carddatabase/filter_string_test.cpp b/tests/carddatabase/filter_string_test.cpp
index c6d68be1f..56f33825c 100644
--- a/tests/carddatabase/filter_string_test.cpp
+++ b/tests/carddatabase/filter_string_test.cpp
@@ -2,6 +2,8 @@
 #include "test_card_database_path_provider.h"
 
 #include "gtest/gtest.h"
+#include <libcockatrice/card/card_info.h>
+#include <libcockatrice/card/printing/printing_info.h>
 #include <libcockatrice/filters/filter_string.h>
 #include <libcockatrice/interfaces/noop_card_preference_provider.h>
 #include <libcockatrice/interfaces/noop_card_set_priority_controller.h>
@@ -71,10 +73,71 @@ QUERY(Color2, cat, "c:gw", true)
 QUERY(Color3, cat, "c!g", true)
 QUERY(Color4, cat, "c!gw", false)
 
+QUERY(SetCodeCaseInsensitive1, cat, "set:cat", true)
+QUERY(SetCodeCaseInsensitive2, cat, "set:CAT", true)
+QUERY(SetCodeCaseInsensitive3, cat, "set:CAt", true)
+QUERY(SetCodeShortForm, cat, "e:cat", true)
+QUERY(SetCodeWrongSet, cat, "set:who", false)
+QUERY(SetCodeWrongSet2, doctor, "set:cat", false)
+
 QUERY(BracketNextToUnquotedString, cat, "(o:woof OR o:meow)", true)
 
 } // namespace
 
+class SetQuery : public ::testing::Test
+{
+protected:
+    void SetUp() override
+    {
+        // EOE and EOC share a release date, like a set and its Commander counterpart.
+        const QDate sharedReleaseDate(2026, 3, 13);
+        mainSet = CardSet::newInstance(&controller, "EOE", "Edge of Eternities", "expansion", sharedReleaseDate,
+                                       CardSet::PriorityPrimary);
+        commanderSet = CardSet::newInstance(&controller, "EOC", "Edge of Eternities Commander", "commander",
+                                            sharedReleaseDate, CardSet::PrioritySecondary);
+
+        inBothSets = newCardWithPrintings({{"EOE", mainSet}, {"EOC", commanderSet}});
+        onlyInCommanderSet = newCardWithPrintings({{"EOC", commanderSet}});
+    }
+
+    CardInfoPtr newCardWithPrintings(const QList<QPair<QString, CardSetPtr>> &printings)
+    {
+        SetToPrintingsMap setsInfo;
+        for (const auto &printing : printings) {
+            setsInfo[printing.first].append(PrintingInfo(printing.second));
+        }
+        return CardInfo::newInstance("Test Card", "", false, {}, {}, {}, setsInfo, CardInfo::UiAttributes());
+    }
+
+    NoopCardSetPriorityController controller;
+    CardSetPtr mainSet;
+    CardSetPtr commanderSet;
+    CardInfoPtr inBothSets;
+    CardInfoPtr onlyInCommanderSet;
+};
+
+TEST_F(SetQuery, ExactMatchSeparatesSameDaySets)
+{
+    EXPECT_TRUE(FilterString("set:EOE").check(inBothSets));
+    EXPECT_TRUE(FilterString("e:EOE").check(inBothSets));
+    EXPECT_TRUE(FilterString("set:EOC").check(inBothSets));
+    EXPECT_FALSE(FilterString("set:EOE").check(onlyInCommanderSet));
+    EXPECT_TRUE(FilterString("set:EOC").check(onlyInCommanderSet));
+}
+
+TEST_F(SetQuery, ExactMatchIsCaseInsensitive)
+{
+    EXPECT_TRUE(FilterString("set:eoe").check(inBothSets));
+    EXPECT_TRUE(FilterString("set:EoE").check(inBothSets));
+    EXPECT_FALSE(FilterString("set:eoe").check(onlyInCommanderSet));
+}
+
+TEST_F(SetQuery, NotEqualsMatchesPrintingsOutsideTheSet)
+{
+    EXPECT_FALSE(FilterString("set!EOE").check(inBothSets));
+    EXPECT_TRUE(FilterString("set!EOE").check(onlyInCommanderSet));
+}
+
 int main(int argc, char **argv)
 {
     ::testing::InitGoogleTest(&argc, argv);