diff --git a/doc/RELEASE-NOTES.md b/doc/RELEASE-NOTES.md
index 45ed97f96..045a64b3b 100644
--- a/doc/RELEASE-NOTES.md
+++ b/doc/RELEASE-NOTES.md
@@ -20,6 +20,7 @@ This is work in progress and may not always be a stable version.
   * Variable comparisons now support `>`, `>=`, `<`, `<=` in addition
     to `==` and `!=`. Uses natural ordering, so version strings and
     numbers compare correctly. Example: `@if $MAXCONNECTIONS >= 1024`.
+  * Support `@else`: `@if ... @else ... @endif`.
 
 ### Changes:
 * [GeoIP](https://www.unrealircd.org/docs/GeoIP):
diff --git a/include/struct.h b/include/struct.h
index 0936ede8e..2c4830ea6 100644
--- a/include/struct.h
+++ b/include/struct.h
@@ -1610,7 +1610,8 @@ typedef enum PreprocessorItem {
 	PREPROCESSOR_ERROR		= 0,
 	PREPROCESSOR_DEFINE		= 1,
 	PREPROCESSOR_IF			= 2,
-	PREPROCESSOR_ENDIF		= 3
+	PREPROCESSOR_ENDIF		= 3,
+	PREPROCESSOR_ELSE		= 4
 } PreprocessorItem;
 
 typedef enum PreprocessorPhase {
@@ -1659,6 +1660,7 @@ struct ConditionalConfig
 	ConfigIfCondition condition; /**< See ConfigIfCondition, one of: IF_* */
 	int negative; /**< For ! conditions */
 	CompareOp compare_op; /**< Only for IF_VALUE */
+	int had_else; /**< Set to 1 after @else, to prevent duplicate @else */
 	char *name; /**< Name of the variable or module */
 	char *opt; /**< Only for IF_VALUE */
 };
diff --git a/src/conf.c b/src/conf.c
index de6d1bb87..6184846e7 100644
--- a/src/conf.c
+++ b/src/conf.c
@@ -1294,6 +1294,35 @@ ConfigFile *config_parse_with_offset(const char *filename, char *confdata, unsig
 					cc->priority = preprocessor_level;
 					AddListItem(cc, cc_list);
 				} else
+				if (n == PREPROCESSOR_ELSE)
+				{
+					ConditionalConfig *cc_item;
+					if (preprocessor_level == 0)
+					{
+						config_error("%s:%i: @else unexpected. There was no preceding unclosed @if.",
+							filename, linenumber);
+						errors++;
+					} else
+					{
+						/* Find the condition at the current nesting level and flip it */
+						for (cc_item = cc_list; cc_item; cc_item = cc_item->next)
+						{
+							if (cc_item->priority == preprocessor_level)
+							{
+								if (cc_item->had_else)
+								{
+									config_error("%s:%i: duplicate @else for the same @if block.",
+										filename, linenumber);
+									errors++;
+									goto breakout;
+								}
+								cc_item->negative = cc_item->negative ? 0 : 1;
+								cc_item->had_else = 1;
+								break;
+							}
+						}
+					}
+				} else
 				if (n == PREPROCESSOR_ENDIF)
 				{
 					if (preprocessor_level == 0)
diff --git a/src/conf_preprocessor.c b/src/conf_preprocessor.c
index 093e0b8be..35a33211d 100644
--- a/src/conf_preprocessor.c
+++ b/src/conf_preprocessor.c
@@ -108,6 +108,7 @@ PreprocessorItem evaluate_preprocessor_if(char *statement, const char *filename,
 	 * !file-exists("something")
 	 * defined($XYZ)
 	 * !defined($XYZ)
+	 * @else is also supported (handled in conf.c, not here).
 	 * We do not support && or || or anything else at this time.
 	 */
 	skip_whitespace(&p);
@@ -320,6 +321,8 @@ PreprocessorItem  parse_preprocessor_item(char *start, char *end, const char *fi
 		return evaluate_preprocessor_define(buf+7, filename, linenumber);
 	else if (!strncmp(buf, "@if ", 4))
 		return evaluate_preprocessor_if(buf+4, filename, linenumber, cc);
+	else if (!strncmp(buf, "@else", 5))
+		return PREPROCESSOR_ELSE;
 	else if (!strncmp(buf, "@endif", 6))
 		return PREPROCESSOR_ENDIF;
 
@@ -369,6 +372,7 @@ void preprocessor_cc_duplicate_list(ConditionalConfig *r, ConditionalConfig **ou
 		cc->condition = r->condition;
 		cc->negative = r->negative;
 		cc->compare_op = r->compare_op;
+		cc->had_else = r->had_else;
 		AddListItem(cc, *out);
 	}
 }