diff --git a/config.pri b/config.pri
index f1f771cb..b7bce121 100644
--- a/config.pri
+++ b/config.pri
@@ -26,9 +26,21 @@ CONFIG(no_opengl) {
 
 !CONFIG(unarr):!CONFIG(7zip) {
 	unix {
-		CONFIG+=unarr
-		  }
+		CONFIG += unarr
+		}
 	win32 {
-			CONFIG+=7zip
-		  }
+		CONFIG += 7zip
+		}
 }
+
+win32:!CONFIG(poppler):!CONFIG(pdfium) {
+	CONFIG += poppler
+}
+
+unix:!macx:!CONFIG(poppler):!CONFIG(pdfium) {
+	CONFIG += poppler
+}
+
+macx:!CONFIG(pdfkit):!CONFIG(pdfium) {
+	CONFIG += pdfkit
+}
\ No newline at end of file