diff --git a/jOOQ/src/main/java/org/jooq/impl/AbstractParseContext.java b/jOOQ/src/main/java/org/jooq/impl/AbstractParseContext.java
index 83ef9ba8b2..e75bd23a91 100644
--- a/jOOQ/src/main/java/org/jooq/impl/AbstractParseContext.java
+++ b/jOOQ/src/main/java/org/jooq/impl/AbstractParseContext.java
@@ -227,6 +227,10 @@ abstract class AbstractParseContext extends AbstractScope {
 
     abstract int afterWhitespace(int p);
 
+    final char lower(char c) {
+        return c >= 'A' && c <= 'Z' ? (char) (c + ('a' - 'A')) : c;
+    }
+
     final char upper(char c) {
         return c >= 'a' && c <= 'z' ? (char) (c - ('a' - 'A')) : c;
     }
@@ -340,6 +344,10 @@ abstract class AbstractParseContext extends AbstractScope {
         return character() == c;
     }
 
+    final boolean peek(char c, int p) {
+        return character(p) == c;
+    }
+
     public final boolean peek(String string) {
         return peek(string, position());
     }
diff --git a/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java b/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
index 016b0f8ddb..c2ac72d064 100644
--- a/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
+++ b/jOOQ/src/main/java/org/jooq/impl/ParserImpl.java
@@ -55,6 +55,7 @@ import static org.jooq.JoinType.JOIN;
 // ...
 // ...
 import static org.jooq.SQLDialect.DERBY;
+import static org.jooq.SQLDialect.FIREBIRD;
 // ...
 import static org.jooq.SQLDialect.HSQLDB;
 // ...
@@ -515,6 +516,7 @@ import static org.jooq.impl.Tools.asInt;
 import static org.jooq.impl.Tools.deleteQueryImpl;
 import static org.jooq.impl.Tools.map;
 import static org.jooq.impl.Tools.normaliseNameCase;
+import static org.jooq.impl.Tools.parseNameCase;
 import static org.jooq.impl.Tools.selectQueryImpl;
 import static org.jooq.impl.Tools.updateQueryImpl;
 import static org.jooq.impl.Tools.BooleanDataKey.DATA_PARSE_ON_CONFLICT;
@@ -755,6 +757,7 @@ import org.jooq.XMLAttributes;
 import org.jooq.XMLTableColumnPathStep;
 import org.jooq.XMLTableColumnsStep;
 import org.jooq.XMLTablePassingStep;
+import org.jooq.conf.ParseNameCase;
 import org.jooq.conf.ParseSearchSchema;
 import org.jooq.conf.ParseUnknownFunctions;
 import org.jooq.conf.ParseUnsupportedSyntax;
@@ -927,7 +930,7 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
 
 
     static final Set<SQLDialect>         SUPPORTS_HASH_COMMENT_SYNTAX             = SQLDialect.supportedBy(MARIADB, MYSQL);
-    static final Set<SQLDialect>         NO_SUPPORT_QUOTED_BUILT_IN_FUNCION_NAMES = SQLDialect.supportedBy(DERBY, HSQLDB);
+    static final Set<SQLDialect>         NO_SUPPORT_QUOTED_BUILT_IN_FUNCION_NAMES = SQLDialect.supportedBy(DERBY, FIREBIRD, HSQLDB);
 
     final Queries parse() {
         return wrap(() -> {
@@ -8982,7 +8985,22 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
 
 
 
-        switch (characterUpper()) {
+        char u = characterUpper();
+
+
+
+
+
+        // [#18480] Allow for quoted built-in function identifiers
+        switch (u) {
+            case '`':
+            case '[':
+            case '"':
+                u = characterNextUpper();
+                break;
+        }
+
+        switch (u) {
 
             // [#8821] Known prefixes so far:
             case ':':
@@ -9419,7 +9437,7 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
 
             case 'L':
                 if (parseFunctionNameIf("LOWER", "LCASE"))
-                    return lower((Field) parseFieldParenthesised());
+                    return DSL.lower((Field) parseFieldParenthesised());
                 else if (parseFunctionNameIf("LPAD", "leftPad"))
                     return parseFunctionArgs3(DSL::lpad, DSL::lpad);
                 else if (parseFunctionNameIf("LTRIM"))
@@ -13603,6 +13621,14 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
              : 0;
     }
 
+    private final char peekQuote(boolean allowAposQuotes, int p) {
+        return peek('"', p) ? '"'
+             : peek('`', p) ? '`'
+             : peek('[', p) ? ']'
+             : allowAposQuotes && peek('\'', p) ? '\''
+             : 0;
+    }
+
     private final DataType<?> parseCastDataType() {
         char character = characterUpper();
 
@@ -15287,8 +15313,41 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
 
         int skip = afterWhitespace(p, peekIntoParens) - p;
 
+        // [#18480] Function names are allowed to be quoted
+        char quoteEnd = requireFunction ? peekQuote(false, p + skip) : 0;
+        boolean quoted = quoteEnd != 0;
+        ParseNameCase nameCase = null;
+
+        if (quoted) {
+            if (NO_SUPPORT_QUOTED_BUILT_IN_FUNCION_NAMES.contains(parseDialect()))
+                return false;
+
+            nameCase = parseNameCase(configuration);
+            switch (parseDialect()) {
+
+
+
+
+
+
+                default:
+                    caseSensitive =
+                           nameCase != ParseNameCase.AS_IS
+                        && nameCase != ParseNameCase.LOWER;
+                    break;
+            }
+
+            skip++;
+        }
+
         for (int i = 0; i < length; i++) {
             char c = keyword.charAt(i);
+
+            if (caseSensitive && (
+                nameCase == ParseNameCase.LOWER_IF_UNQUOTED ||
+                nameCase == ParseNameCase.LOWER))
+                c = lower(c);
+
             int pos = p + i + skip;
 
             switch (c) {
@@ -15313,6 +15372,15 @@ final class DefaultParseContext extends AbstractParseContext implements ParseCon
 
         int pos = p + length + skip;
 
+        if (quoted) {
+            if (character(pos) == quoteEnd) {
+                pos++;
+                skip++;
+            }
+            else
+                return false;
+        }
+
         // [#8806] A keyword that is followed by a period is very likely an identifier
         if (isIdentifierPart(pos) || character(pos) == '.')
             return false;
diff --git a/jOOQ/src/main/java/org/jooq/impl/Tools.java b/jOOQ/src/main/java/org/jooq/impl/Tools.java
index 2f1a514d02..80bc37b655 100644
--- a/jOOQ/src/main/java/org/jooq/impl/Tools.java
+++ b/jOOQ/src/main/java/org/jooq/impl/Tools.java
@@ -7212,7 +7212,7 @@ final class Tools {
      * Get the {@link ParseNameCase}, looking up the default value from the
      * parse dialect.
      */
-    private static final ParseNameCase parseNameCase(Configuration configuration) {
+    static final ParseNameCase parseNameCase(Configuration configuration) {
         ParseNameCase result = defaultIfNull(configuration.settings().getParseNameCase(), ParseNameCase.DEFAULT);
 
         if (result == ParseNameCase.DEFAULT) {