diff --git a/.gitlab-ci.yml b/.gitlab-ci.yml
index d9daeca..c8e99f2 100644
--- a/.gitlab-ci.yml
+++ b/.gitlab-ci.yml
@@ -24,7 +24,7 @@ build-job:       # This job runs in the build stage, which runs first.
     - linux
   before_script:
     - apt update
-    - apt install -y cmake libgtk2.0-dev
+    - apt install -y cmake libgtkmm-3.0-dev
   script:
     - echo "Configuring"
     - cmake -B build .
diff --git a/CMakeLists.txt b/CMakeLists.txt
index d576911..e2bee1c 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -3,8 +3,8 @@ set(CMAKE_CXX_STANDARD 17)
 
 project(PiCamera)
 
-# Find gtk+-2.0 library
+# Find gtk+-4.0 library
 find_package(PkgConfig REQUIRED)
-pkg_check_modules(GTK2 REQUIRED gtk+-2.0)
+pkg_check_modules(GTK REQUIRED gtkmm-3.0)
 
 add_subdirectory(src)
diff --git a/README.md b/README.md
index 29a9bb0..46482cb 100644
--- a/README.md
+++ b/README.md
@@ -5,7 +5,7 @@ Camera for Raspberry Pi in C++ :)
 Requirements:
 ```
 cmake
-libgtk2.0-dev
+libgtkmm-3.0-dev
 ```
 
 Then:
diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index 2357e16..a38bfed 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -5,16 +5,16 @@ add_executable(
 target_include_directories(
     JAMCS
     PRIVATE
-    ${GTK2_INCLUDE_DIRS}
+    ${GTK_INCLUDE_DIRS}
 )
 target_link_directories(
     JAMCS
     PRIVATE
-    ${GTK2_LIBRARY_DIRS}
+    ${GTK_LIBRARY_DIRS}
 )
 target_link_libraries(
     JAMCS
     PRIVATE
-    ${GTK2_LIBRARIES}
+    ${GTK_LIBRARIES}
 )
-add_definitions (${GTK2_CFLAGS_OTHER})
+add_definitions (${GTK_CFLAGS_OTHER})