diff --git a/makefile b/makefile
index eef4e14d0d..7782850780 100755
--- a/makefile
+++ b/makefile
@@ -566,7 +566,8 @@ ifdef msvc
 	cflags = -nologo -DAVIAN_VERSION=\"$(version)\" -D_JNI_IMPLEMENTATION_ \
 		-DUSE_ATOMIC_OPERATIONS -DAVIAN_JAVA_HOME=\"$(javahome)\" \
 		-DAVIAN_EMBED_PREFIX=\"$(embed-prefix)\" \
-		-Fd$(build)/$(name).pdb -I"$(zlib)/include" -I$(src) -I"$(build)" \
+		-Fd$(build)/$(name).pdb -I"$(zlib)/include" -I$(src) -I$(classpath-src) \
+		-I"$(build)" \
 		-I"$(windows-java-home)/include" -I"$(windows-java-home)/include/win32" \
 		-DTARGET_BYTES_PER_WORD=$(pointer-size)