diff --git a/CMakeLists.txt b/CMakeLists.txt
index d1d3653..3d61503 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -2,7 +2,7 @@ project(poppler)
 
 cmake_minimum_required(VERSION 3.10.0 FATAL_ERROR)
 
-set(CMAKE_MODULE_PATH ${CMAKE_SOURCE_DIR}/cmake/modules)
+list(APPEND CMAKE_MODULE_PATH ${PROJECT_SOURCE_DIR}/cmake/modules)
 
 include(PopplerDefaults)
 include(PopplerMacros)
@@ -85,7 +85,7 @@ option(EXTRA_WARN "Enable extra compile warnings" OFF)
 
 set(CMAKE_INSTALL_RPATH_USE_LINK_PATH TRUE)
 
-set(TESTDATADIR "${CMAKE_SOURCE_DIR}/../test" CACHE STRING "Specify test data dir.")
+set(TESTDATADIR "${PROJECT_SOURCE_DIR}/../test" CACHE STRING "Specify test data dir.")
 if(NOT (EXISTS ${TESTDATADIR} AND EXISTS ${TESTDATADIR}/test-poppler.c))
   message(WARNING "
  No test data found in $testdatadir.
@@ -837,4 +837,4 @@ add_custom_target(dist
         COMMAND tar -C ${CMAKE_BINARY_DIR} -rf ${CMAKE_BINARY_DIR}/${ARCHIVE_NAME}.tar ChangeLog --transform='s,,${ARCHIVE_NAME}/,' --owner root:0 --group root:0
         COMMAND tar -C ${CMAKE_BINARY_DIR} -rf ${CMAKE_BINARY_DIR}/${ARCHIVE_NAME}.tar glib/reference/html --transform='s,,${ARCHIVE_NAME}/,' --owner root:0 --group root:0
         COMMAND xz -9 ${CMAKE_BINARY_DIR}/${ARCHIVE_NAME}.tar
-    WORKING_DIRECTORY ${CMAKE_SOURCE_DIR})
+    WORKING_DIRECTORY ${PROJECT_SOURCE_DIR})
diff --git a/cpp/tests/CMakeLists.txt b/cpp/tests/CMakeLists.txt
index 10ac0b3..adbcfcd 100644
--- a/cpp/tests/CMakeLists.txt
+++ b/cpp/tests/CMakeLists.txt
@@ -2,7 +2,7 @@ include_directories(
   ${CMAKE_CURRENT_SOURCE_DIR}
   ${CMAKE_CURRENT_SOURCE_DIR}/..
   ${CMAKE_CURRENT_BINARY_DIR}/..
-  ${CMAKE_SOURCE_DIR}/utils
+  ${PROJECT_SOURCE_DIR}/utils
 )
 
 macro(CPP_ADD_SIMPLETEST exe)
@@ -17,8 +17,8 @@ macro(CPP_ADD_SIMPLETEST exe)
   endif()
 endmacro(CPP_ADD_SIMPLETEST)
 
-cpp_add_simpletest(poppler-dump poppler-dump.cpp ${CMAKE_SOURCE_DIR}/utils/parseargs.cc)
-cpp_add_simpletest(poppler-render poppler-render.cpp ${CMAKE_SOURCE_DIR}/utils/parseargs.cc)
+cpp_add_simpletest(poppler-dump poppler-dump.cpp ${PROJECT_SOURCE_DIR}/utils/parseargs.cc)
+cpp_add_simpletest(poppler-render poppler-render.cpp ${PROJECT_SOURCE_DIR}/utils/parseargs.cc)
 
 if(ENABLE_FUZZER)
   cpp_add_simpletest(doc_fuzzer ./fuzzing/doc_fuzzer.cc)
diff --git a/glib/CMakeLists.txt b/glib/CMakeLists.txt
index 007b2b9..75ecb35 100644
--- a/glib/CMakeLists.txt
+++ b/glib/CMakeLists.txt
@@ -81,9 +81,9 @@ set(poppler_glib_SRCS
 )
 set(poppler_glib_generated_SRCS
   ${CMAKE_CURRENT_BINARY_DIR}/poppler-enums.c
-  ${CMAKE_SOURCE_DIR}/poppler/CairoFontEngine.cc
-  ${CMAKE_SOURCE_DIR}/poppler/CairoOutputDev.cc
-  ${CMAKE_SOURCE_DIR}/poppler/CairoRescaleBox.cc
+  ${PROJECT_SOURCE_DIR}/poppler/CairoFontEngine.cc
+  ${PROJECT_SOURCE_DIR}/poppler/CairoOutputDev.cc
+  ${PROJECT_SOURCE_DIR}/poppler/CairoRescaleBox.cc
 )
 add_library(poppler-glib ${poppler_glib_SRCS} ${poppler_glib_generated_SRCS})
 generate_export_header(poppler-glib EXPORT_MACRO_NAME POPPLER_PUBLIC EXPORT_FILE_NAME "${CMAKE_CURRENT_BINARY_DIR}/poppler-macros.h")
diff --git a/glib/reference/CMakeLists.txt b/glib/reference/CMakeLists.txt
index 1551540..e309186 100644
--- a/glib/reference/CMakeLists.txt
+++ b/glib/reference/CMakeLists.txt
@@ -1,7 +1,7 @@
 add_custom_command(
   OUTPUT ${CMAKE_CURRENT_BINARY_DIR}/glib-docs-build.stamp
   DEPENDS poppler-glib
-  COMMAND ${CMAKE_SOURCE_DIR}/make-glib-api-docs --src-dir=${CMAKE_SOURCE_DIR} --build-dir=${CMAKE_BINARY_DIR}
+  COMMAND ${PROJECT_SOURCE_DIR}/make-glib-api-docs --src-dir=${PROJECT_SOURCE_DIR} --build-dir=${CMAKE_BINARY_DIR}
   COMMAND touch ${CMAKE_CURRENT_BINARY_DIR}/glib-docs-build.stamp
 )
 
diff --git a/test/CMakeLists.txt b/test/CMakeLists.txt
index b9251e0..4d3562d 100644
--- a/test/CMakeLists.txt
+++ b/test/CMakeLists.txt
@@ -19,7 +19,7 @@ if (GTK_FOUND)
   )
 
   include_directories(
-    ${CMAKE_SOURCE_DIR}/glib
+    ${PROJECT_SOURCE_DIR}/glib
     ${CMAKE_BINARY_DIR}/glib
   )
 
@@ -33,9 +33,9 @@ if (GTK_FOUND)
 
     set (pdf_inspector_SRCS
       pdf-inspector.cc
-      ${CMAKE_SOURCE_DIR}/poppler/CairoFontEngine.cc
-      ${CMAKE_SOURCE_DIR}/poppler/CairoOutputDev.cc
-      ${CMAKE_SOURCE_DIR}/poppler/CairoRescaleBox.cc
+      ${PROJECT_SOURCE_DIR}/poppler/CairoFontEngine.cc
+      ${PROJECT_SOURCE_DIR}/poppler/CairoOutputDev.cc
+      ${PROJECT_SOURCE_DIR}/poppler/CairoRescaleBox.cc
     )
     poppler_add_test(pdf-inspector BUILD_GTK_TESTS ${pdf_inspector_SRCS})
     target_link_libraries(pdf-inspector ${CAIRO_LIBRARIES} ${FREETYPE_LIBRARIES} ${common_libs} ${GTK3_LIBRARIES} poppler)
diff --git a/utils/CMakeLists.txt b/utils/CMakeLists.txt
index ce0ce16..5a6645f 100644
--- a/utils/CMakeLists.txt
+++ b/utils/CMakeLists.txt
@@ -25,9 +25,9 @@ if (HAVE_CAIRO)
   set(pdftocairo_SOURCES ${common_srcs}
     pdftocairo.cc
     pdftocairo-win32.cc
-    ${CMAKE_SOURCE_DIR}/poppler/CairoFontEngine.cc
-    ${CMAKE_SOURCE_DIR}/poppler/CairoOutputDev.cc
-    ${CMAKE_SOURCE_DIR}/poppler/CairoRescaleBox.cc
+    ${PROJECT_SOURCE_DIR}/poppler/CairoFontEngine.cc
+    ${PROJECT_SOURCE_DIR}/poppler/CairoOutputDev.cc
+    ${PROJECT_SOURCE_DIR}/poppler/CairoRescaleBox.cc
   )
   include_directories(
     ${CMAKE_CURRENT_SOURCE_DIR}