diff --git a/src/big-int/makefile b/src/big-int/makefile
index 96492d98b84..abc063522a7 100644
--- a/src/big-int/makefile
+++ b/src/big-int/makefile
@@ -1,7 +1,8 @@
+SRC = bigint-func.cc bigint.cc
+
 include ../config.inc
 include ../common
 
-SRC = bigint-func.cc bigint.cc
 CLEANFILES = big-int$(LIBEXT)
 
 all: big-int$(LIBEXT)
diff --git a/src/common b/src/common
index 742f872abff..276f7f3a6b4 100644
--- a/src/common
+++ b/src/common
@@ -270,6 +270,7 @@ sources: Makefile
 # endif
 
 D_FILES1 = $(SRC:.c=$(DEPEXT))
-D_FILES = $(D_FILES1:.cpp=$(DEPEXT))
+D_FILES2 = $(D_FILES1:.cc=$(DEPEXT))
+D_FILES = $(D_FILES2:.cpp=$(DEPEXT))
 
 -include $(D_FILES)