diff --git a/CMakeLists.txt b/CMakeLists.txt
index b1ac5d02..5235356b 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -27,11 +27,13 @@ if(JSONSCHEMA_TESTS)
 endif()
 
 # As a sanity check
-file(READ "${PROJECT_SOURCE_DIR}/action.yml" ACTION_YML)
-string(FIND "${ACTION_YML}" "${PROJECT_VERSION}" ACTION_YML_HAS_VERSION)
-if(${ACTION_YML_HAS_VERSION} EQUAL -1)
-  message(FATAL_ERROR
-    "The GitHub Action definition must set the correct version: ${PROJECT_VERSION}")
+if(EXISTS "${PROJECT_SOURCE_DIR}/action.yml")
+  file(READ "${PROJECT_SOURCE_DIR}/action.yml" ACTION_YML)
+  string(FIND "${ACTION_YML}" "${PROJECT_VERSION}" ACTION_YML_HAS_VERSION)
+  if(${ACTION_YML_HAS_VERSION} EQUAL -1)
+    message(FATAL_ERROR
+      "The GitHub Action definition must set the correct version: ${PROJECT_VERSION}")
+  endif()
 endif()
 
 # Packaging
diff --git a/Dockerfile b/Dockerfile
index 518406a1..cc1f99d8 100644
--- a/Dockerfile
+++ b/Dockerfile
@@ -9,7 +9,12 @@ RUN DEBIAN_FRONTEND=noninteractive apt-get install -y --no-install-recommends tz
 # Tools to compile:
 RUN apt install -y build-essential cmake clang-format shellcheck curl
 
-COPY . /compile
+COPY cmake /compile/cmake
+COPY src /compile/src
+COPY test /compile/test
+COPY vendor /compile/vendor
+COPY CMakeLists.txt /compile/CMakeLists.txt
+COPY Makefile /compile/Makefile
 WORKDIR /compile
 
 RUN make configure
@@ -18,4 +23,4 @@ RUN make compile
 FROM ubuntu
 COPY --from=compiler /compile/build/dist/bin/jsonschema /usr/local/bin/jsonschema
 WORKDIR /schema
-ENTRYPOINT ["/usr/local/bin/jsonschema"]
\ No newline at end of file
+ENTRYPOINT ["/usr/local/bin/jsonschema"]