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--- a/src/mk/localdefs.in
+++ b/src/mk/localdefs.in
@@ -4,9 +4,12 @@
 
 LIBICONV=@LIBICONV@
 INCICONV=@INCICONV@
-RECOLL_PREFIX=@prefix@
+
+prefix = @prefix@
+datadir = @datadir@
+RECOLL_DATADIR = ${datadir}/recoll
 
 LOCALCXXFLAGS = $(INCICONV) $(XAPIANCXXFLAGS) \
-	      -DRECOLL_PREFIX=\"$(RECOLL_PREFIX)\"
+	      -DRECOLL_DATADIR=\"$(RECOLL_DATADIR)\"
 
 CXXFLAGS = -g