diff --git a/mkspecs/features/common_pre.prf b/mkspecs/features/common_pre.prf
index 3f09c08e0..57ea539a5 100644
--- a/mkspecs/features/common_pre.prf
+++ b/mkspecs/features/common_pre.prf
@@ -100,7 +100,7 @@ include(defines.pri)
 # EXTERNALSROOT = /path/to/externals
 
 isEmpty(EXTERNALSROOT) {
-    EXTERNALSROOT = $$(VATSIM_EXTERNAL_DIR)
+    EXTERNALSROOT = $$(SWIFT_EXTERNALS_DIR)
 }
 
 isEmpty(EXTERNALSROOT) {
@@ -108,7 +108,7 @@ isEmpty(EXTERNALSROOT) {
 }
 
 !exists("$$EXTERNALSROOT/common/include"):in_full_qmake {
-    error("Could not find externals in $$EXTERNALSROOT. Please install it!")
+    error("Could not find externals in $${EXTERNALSROOT}. Please install them!")
 }
 
 ################################