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--- a/src/mk/localdefs.in
+++ b/src/mk/localdefs.in
@@ -5,5 +5,5 @@
 LIBICONV=@LIBICONV@
 INCICONV=@INCICONV@
 
-LOCALCXXFLAGS = $(INCICONV) $(XAPIANCXXFLAGS)
+LOCALCXXFLAGS = $(INCICONV) $(XAPIANCXXFLAGS) -DRECOLL_PREFIX=\"@prefix@\"