diff --git a/Dockerfile b/Dockerfile
index 838a306..d53dc11 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,7 +9,7 @@ RUN apk add --no-cache \
 
 RUN git clone --depth=1 https://github.com/cathugger/mkp224o \
     && cd mkp224o \
-    && sed -i 's/^\(CFLAGS= .*\)$/\1 -static/' Makefile.in \
+    && sed -i 's/^\(CFLAGS= .*\)$/\1 -static/' GNUmakefile.in \
     && ./autogen.sh
 
 COPY matrix-build.sh .