diff --git a/libcockatrice_filters/libcockatrice/filters/filter_string.cpp b/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
index bc137b0f6..0acc0eca0 100644
--- a/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
+++ b/libcockatrice_filters/libcockatrice/filters/filter_string.cpp
@@ -43,31 +43,31 @@ SomewhatComplexQueryPart <- [(] QueryPartList [)] / QueryPart
 QueryPart <- NotQuery / SetQuery / RarityQuery / CMCQuery / FormatQuery / PowerQuery / ToughnessQuery / ColorQuery / TypeQuery / OracleQuery / FieldQuery / GenericQuery
 
 NotQuery <- ('NOT' ws/'-') SomewhatComplexQueryPart
-SetQuery <- ('e'/'set') SetQueryValue
-SetQueryValue <- ([=:] FlexStringValue) / (<[!][=]?> FlexStringValue) / SetExpression
-OracleQuery <- 'o' [:] MatcherString
+SetQuery <- ('e'/'set') ws? SetQueryValue
+SetQueryValue <- ([=:] ws? FlexStringValue) / (<[!][=]?> ws? FlexStringValue) / SetExpression
+OracleQuery <- 'o' ws? [:] ws? MatcherString
 
 
 CMCQuery <- ('cmc'/'mv') ws? NumericExpression
 PowerQuery <- [Pp] 'ow' 'er'? ws? NumericExpression
 ToughnessQuery <- [Tt] 'ou' 'ghness'? ws? NumericExpression
 
-RarityQuery <- [rR] ':' Rarity
+RarityQuery <- [rR] ws? ':' ws? Rarity
 Rarity <- [Cc] 'ommon'? / [Uu] 'ncommon'? / [Rr] 'are'? / [Mm] 'ythic'? / [Ss] 'pecial'? / [a-zA-Z] [a-z]*
 
-FormatQuery <- 'f' ':' Format / Legality ':' Format
+FormatQuery <- 'f' ws? ':' ws? Format / Legality ws? ':' ws? Format
 Format <- [a-zA-Z] [a-z]*
 Legality <- [Ll] 'egal'? / [Bb] 'anned'? / [Rr] 'estricted'
 
 
-TypeQuery <- [tT] 'ype'? [:] StringValue
+TypeQuery <- [tT] 'ype'? ws? [:] ws? StringValue
 
 Color <- < [Ww] 'hite'? / [Uu] / [Bb] 'lack'? / [Rr] 'ed'? / [Gg] 'reen'?  / [Bb] 'lue'? >
 ColorEx <- Color / [mc]
 
-ColorQuery <- [cC] 'olor'? <[iI]?> <[:!]> ColorEx*
+ColorQuery <- [cC] 'olor'? <[iI]?> ws? <[:!]> ws? ColorEx*
 
-FieldQuery <- String [:] MatcherString / String ws? NumericExpression
+FieldQuery <- String ws? [:] ws? MatcherString / String ws? NumericExpression
 
 NonDoubleQuoteUnlessEscaped <- '\\\"'. / !["].
 NonSingleQuoteUnlessEscaped <- "\\\'". / !['].
diff --git a/tests/carddatabase/filter_string_test.cpp b/tests/carddatabase/filter_string_test.cpp
index 95225e28c..e561db590 100644
--- a/tests/carddatabase/filter_string_test.cpp
+++ b/tests/carddatabase/filter_string_test.cpp
@@ -99,6 +99,17 @@ QUERY(SetCodeWrongSet2, doctor, "set:cat", false)
 
 QUERY(BracketNextToUnquotedString, cat, "(o:woof OR o:meow)", true)
 
+// Spaces around the colon are optional for all field queries (e.g. "o: flying")
+QUERY(OracleSpaceAfterColon, cat, "o: meow", true)
+QUERY(OracleSpaceBeforeColon, cat, "o :meow", true)
+QUERY(OracleSpacesAroundColon, cat, "o : meow", true)
+QUERY(OracleSpaceAfterColonNoMatch, cat, "o: woof", false)
+QUERY(TypeSpaceAfterColon, cat, "t: creature", true)
+QUERY(FieldSpaceAfterColon, cat, "pt: \"3/3\"", true)
+QUERY(ColorSpaceAfterColon, cat, "c: g", true)
+QUERY(ColorSpaceBeforeOperator, cat, "c !g", true)
+QUERY(SetSpaceAfterColon, cat, "set: cat", true)
+
 CardInfoPtr localizedCat()
 {
     CardInfoPtr localized = CardInfo::newInstance("Cat", "Meow!", false, {}, {}, {}, {}, {});
@@ -107,6 +118,22 @@ CardInfoPtr localizedCat()
     return localized;
 }
 
+CardInfoPtr greenIdentityCard()
+{
+    return CardInfo::newInstance("Identity Cat", "", false, {{"colors", "G"}, {"coloridentity", "G"}}, {}, {}, {}, {});
+}
+
+// Whitespace belongs around the separator, never inside an operator token: "c i: g" must not
+// be read as the color-identity operator "ci" (it is a generic "c" AND a field query on "i").
+TEST_F(CardQuery, ColorIdentityOperatorIsNotSplitByWhitespace)
+{
+    const CardData identityCard = greenIdentityCard();
+    ASSERT_TRUE(FilterString("ci:g").check(identityCard));
+    ASSERT_TRUE(FilterString("ci: g").check(identityCard));
+    ASSERT_TRUE(FilterString("ci : g").check(identityCard));
+    ASSERT_FALSE(FilterString("c i: g").check(identityCard));
+}
+
 TEST_F(CardQuery, SearchLanguageEnglishMatchesOnlyEnglish)
 {
     const CardData localized = localizedCat();
@@ -136,6 +163,13 @@ TEST_F(CardQuery, SearchLanguageBothMatchesEitherLanguage)
     ASSERT_TRUE(FilterString("Kater", CardSearchLanguage{"de", SearchLanguageMode::Both}).check(localized));
 }
 
+TEST_F(CardQuery, SearchLanguageBothMatchesOracleTextWithSpaceAfterColon)
+{
+    const CardData localized = localizedCat();
+    ASSERT_TRUE(FilterString("o: Meow", CardSearchLanguage{"de", SearchLanguageMode::Both}).check(localized));
+    ASSERT_TRUE(FilterString("o: miaut", CardSearchLanguage{"de", SearchLanguageMode::Both}).check(localized));
+}
+
 TEST_F(CardQuery, SearchLanguageIsBoundPerInstance)
 {
     const CardData localized = localizedCat();