diff --git a/samples/gitchurn/README.md b/samples/gitchurn/README.md
index 740ba3413e0..dc6c15122e7 100644
--- a/samples/gitchurn/README.md
+++ b/samples/gitchurn/README.md
@@ -1,6 +1,7 @@
 # GIT frequency analyzer
 
  This example shows how one could perform statistics on Git repository.
+libgit2 is required for this to work (`apt-get install libgit2-dev`).
 
 To build use `./build.sh` script without arguments (or specify `TARGET` variable if cross-compiling).
 
diff --git a/samples/opengl/README.md b/samples/opengl/README.md
index 9a682854a00..de89d21b723 100644
--- a/samples/opengl/README.md
+++ b/samples/opengl/README.md
@@ -1,6 +1,7 @@
 # OpenGL application
 
- This example shows interaction with OpenGL library, to render classical 3D test model.
+ This example shows interaction with OpenGL library, to render classical 3D test model. Linux build requires `apt-get install freeglut3-dev` or similar,
+MacOS shall work as is.
 
 To build use `./build.sh` script without arguments (or specify `TARGET` variable if cross-compiling).
 
diff --git a/samples/opengl/build.sh b/samples/opengl/build.sh
index d24447518dc..67b48a68891 100755
--- a/samples/opengl/build.sh
+++ b/samples/opengl/build.sh
@@ -23,4 +23,4 @@ COMPILER_ARGS=${!var} # add -opt for an optimized build.
 
 interop -def:$DIR/opengl.def -target:$TARGET || exit 1
 # OpenGL stubs are rather big, so we need more heap space.
-konanc -J-Xmx2G -target $TARGET opengl $DIR/OpenGlTeapot.kt -nativelibrary openglstubs.bc -linkerArgs "$LINKER_ARGS" -o OpenGlTeapot.kexe || exit 1
+konanc -J-Xmx3G -target $TARGET opengl $DIR/OpenGlTeapot.kt -nativelibrary openglstubs.bc -linkerArgs "$LINKER_ARGS" -o OpenGlTeapot.kexe || exit 1