diff --git a/CMakeLists.txt b/CMakeLists.txt
index c0190c0..6488376 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -36,7 +36,7 @@ add_test(
 )
 
 #-- spectator library
-add_library(spectator
+add_library(spectator SHARED
     "spectator/logger.cc"
     "spectator/publisher.cc"
     "spectator/config.h"
diff --git a/build.sh b/build.sh
index fcedf35..af7998f 100755
--- a/build.sh
+++ b/build.sh
@@ -4,16 +4,21 @@ set -e
 
 # usage: ./build.sh [clean|clean --confirm|skiptest]
 
-BUILD_DIR=cmake-build
-# Choose: Debug, Release, RelWithDebInfo and MinSizeRel. Use Debug for asan checking locally.
-BUILD_TYPE=Debug
+if [[ -z "$BUILD_DIR" ]]; then
+  BUILD_DIR="cmake-build"
+fi
+
+if [[ -z "$BUILD_TYPE" ]]; then
+  # Choose: Debug, Release, RelWithDebInfo and MinSizeRel. Use Debug for asan checking locally.
+  BUILD_TYPE="Debug"
+fi
 
 BLUE="\033[0;34m"
 NC="\033[0m"
 
 if [[ "$1" == "clean" ]]; then
   echo -e "${BLUE}==== clean ====${NC}"
-  rm -rf $BUILD_DIR
+  rm -rf "$BUILD_DIR"
   rm -f spectator/*.inc
   if [[ "$2" == "--confirm" ]]; then
     # remove all packages from the conan cache, to allow swapping between Release/Debug builds
@@ -22,8 +27,10 @@ if [[ "$1" == "clean" ]]; then
 fi
 
 if [[ "$OSTYPE" == "linux-gnu"* ]]; then
-  export CC=gcc-13
-  export CXX=g++-13
+  if [[ -z "$CC" || -z "$CXX" ]]; then
+    export CC=gcc-13
+    export CXX=g++-13
+  fi
 fi
 
 if [[ ! -f "$HOME/.conan2/profiles/default" ]]; then