diff --git a/src/xspice/icm/GNUmakefile.in b/src/xspice/icm/GNUmakefile.in
index 1958103fe..29eb60d94 100644
--- a/src/xspice/icm/GNUmakefile.in
+++ b/src/xspice/icm/GNUmakefile.in
@@ -43,7 +43,7 @@ clean:
 
 
 #-----------------------------------------------------------------------------
-NGSRCDIR = $(CURDIR)/../../../../src
+NGSRCDIR = $(srcdir)/../../
 
 dstring.o : $(NGSRCDIR)/misc/dstring.c $(NGSRCDIR)/include/ngspice/dstring.h
 	$(COMPILE) -I $(NGSRCDIR)/include/ngspice -o $@ -c $<