diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 3a0452b327..9f871f10df 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -61,9 +61,10 @@ if(WIN32)
   list(APPEND CURL_CFILES curl.rc)
 endif()
 
-# CURL_CFILES, CURLX_CFILES, CURL_HFILES come from Makefile.inc
+# CURL_CFILES, CURLX_CFILES, CURL_HFILES, CURLTOOL_LIBCURL_CFILES
+# come from Makefile.inc
 if(BUILD_STATIC_CURL)
-  set(CURLX_CFILES ../lib/dynbuf.c ../lib/base64.c)
+  set(CURLX_CFILES ${CURLTOOL_LIBCURL_CFILES})
 endif()
 
 add_executable(
@@ -80,7 +81,7 @@ add_library(
   curltool # special libcurltool library just for unittests
   STATIC
   EXCLUDE_FROM_ALL
-  ${CURL_CFILES} ${CURLX_CFILES} ${CURL_HFILES}
+  ${CURL_CFILES} ${CURLTOOL_LIBCURL_CFILES} ${CURL_HFILES}
 )
 target_compile_definitions(curltool PUBLIC UNITTESTS CURL_STATICLIB)
 
diff --git a/src/Makefile.inc b/src/Makefile.inc
index edcea2f7ce..b97655ad6b 100644
--- a/src/Makefile.inc
+++ b/src/Makefile.inc
@@ -29,6 +29,11 @@
 # CSRC2 = file4.c file5.c file6.c
 # CSOURCES = $(CSRC1) $(CSRC2)
 
+# libcurl sources to include in curltool lib we use for test binaries
+CURLTOOL_LIBCURL_CFILES = \
+  ../lib/base64.c \
+  ../lib/dynbuf.c
+
 # libcurl has sources that provide functions named curlx_* that aren't part of
 # the official API, but we reuse the code here to avoid duplication.
 CURLX_CFILES = \