4 files changed, 8 insertions, 5 deletions

diff --git a/.github/workflows/build.yml b/.github/workflows/build.yml
index 8ad7bcd..10769c1 100644
--- a/.github/workflows/build.yml
+++ b/.github/workflows/build.yml
@@ -52,7 +52,7 @@ jobs:
 
     strategy:
       matrix:
-        java: [ "11", "17", "21" ]
+        java: [ "15", "17", "21" ]
     name: Build reader on Java ${{ matrix.java }}
     steps:
       - uses: actions/checkout@v4
@@ -88,7 +88,7 @@ jobs:
 
     strategy:
       matrix:
-        java: [ "17", "21" ]
+        java: [ "15", "17", "21" ]
     env:
       # ffs: https://github.com/adoptium/adoptium-support/issues/485 !!!
       # also, add the wolfcrypt JNI path
diff --git a/README.md b/README.md
index f9cbfd7..726be68 100644
--- a/README.md
+++ b/README.md
@@ -36,12 +36,15 @@ There are three parts of ECTester, the JavaCard applet used for testing, the rea
 standalone app which tests software libraries. The target platform for ECTester is Linux, but things should work on
 Windows as well, although testing of standalone libraries will be limited to Java libraries and Microsoft CNG library.
 
+The ECTester parts require different Java versions. Reader and standalone parts require Java >= 15 while the applet build
+will be able to target different JavaCard versions based on the Java version, see [this list](https://github.com/martinpaljak/ant-javacard/wiki/JavaCard-SDK-and-JDK-version-compatibility).
+
 To build ECTester simply do:
 ```bash
 git submodule update --init --recursive       # To initialize submodules (JavaCard SDKs, Microsoft CNG, BoringSSL, ...)
 ./gradlew :applet:buildJavaCard               # To build the applet (cap) -> "applet/build/javacard/applet[221,222,305].cap".
 ./gradlew :reader:uberJar                     # To build the reader tool (jar) -> "reader/build/libs/ECTesterReader.jar"
-./gradlew :standalone:libs                    # To build the native library shims. (Necessary
+./gradlew :standalone:libs                    # To build the native library shims.
 ./gradlew :standalone:uberJar                 # To build the standalone tool (jar) -> "standalone/build/libs/ECTesterStandalone.jar"
 ```
 The applet comes in several flavors, targeting JavaCard `2.2.1`, `2.2.2` and `3.0.5`. The `2.2.2` and later flavors
diff --git a/common/build.gradle.kts b/common/build.gradle.kts
index 0aca7fb..1aff0d7 100644
--- a/common/build.gradle.kts
+++ b/common/build.gradle.kts
@@ -23,5 +23,5 @@ dependencies {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_11
+    sourceCompatibility = JavaVersion.VERSION_15
 }
\ No newline at end of file
diff --git a/standalone/build.gradle.kts b/standalone/build.gradle.kts
index f8d7f9b..5ad3fb4 100644
--- a/standalone/build.gradle.kts
+++ b/standalone/build.gradle.kts
@@ -25,7 +25,7 @@ dependencies {
 }
 
 java {
-    sourceCompatibility = JavaVersion.VERSION_11
+    sourceCompatibility = JavaVersion.VERSION_15
 }
 
 application {