diff --git a/build/jam/BuildSetup b/build/jam/BuildSetup
index 92f28c33ba..ed193ebd3c 100644
--- a/build/jam/BuildSetup
+++ b/build/jam/BuildSetup
@@ -848,8 +848,8 @@ switch $(TARGET_PLATFORM) {
 	case linux		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LINUX ;
 	case freebsd	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_FREEBSD ;
 	case darwin		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_DARWIN ;
-	case cygwin		: TARGET_DEFINES += HAIKU_TARGET_PLATFORM_CYGWIN ;
-	case sunos		: TARGET_DEFINES += HAIKU_TARGET_PLATFORM_SUNOS ;
+	case cygwin		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_CYGWIN ;
+	case sunos		: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_SUNOS ;
 	case libbe_test	: TARGET_DEFINES	+= HAIKU_TARGET_PLATFORM_LIBBE_TEST ;
 }
 
@@ -862,8 +862,8 @@ switch $(HOST_PLATFORM) {
 	case linux		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_LINUX ;
 	case freebsd	: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_FREEBSD ;
 	case darwin		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_DARWIN ;
-	case cygwin		: HOST_DEFINES += HAIKU_HOST_PLATFORM_CYGWIN ;
-	case sunos		: HOST_DEFINES += HAIKU_HOST_PLATFORM_SUNOS ;
+	case cygwin		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_CYGWIN ;
+	case sunos		: HOST_DEFINES	+= HAIKU_HOST_PLATFORM_SUNOS ;
 }