diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index 83806c1..60e394c 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -18,7 +18,7 @@ env:
 
 jobs:
   linux-compat:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04 # latest
     strategy:
       fail-fast: false
       matrix:
@@ -39,7 +39,7 @@ jobs:
         ./linux-container-ci.sh ${{ env.BUILDER_VERSION }} aws-crt-${{ matrix.image }} build -p ${{ env.PACKAGE_NAME }} downstream
 
   linux-compiler-compat:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04 # latest
     strategy:
       matrix:
         compiler:
@@ -62,7 +62,7 @@ jobs:
           ./linux-container-ci.sh ${{ env.BUILDER_VERSION }} aws-crt-${{ env.LINUX_BASE_IMAGE }} build -p ${{ env.PACKAGE_NAME }} --compiler=${{ matrix.compiler }} --spec downstream
 
   clang-sanitizers:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04 # latest
     strategy:
       matrix:
         sanitizers: [",thread", ",address,undefined"]
@@ -74,7 +74,7 @@ jobs:
           ./linux-container-ci.sh ${{ env.BUILDER_VERSION }} aws-crt-${{ env.LINUX_BASE_IMAGE }} build -p ${{ env.PACKAGE_NAME }} --compiler=clang-11 --cmake-extra=-DENABLE_SANITIZERS=ON --cmake-extra=-DSANITIZERS="${{ matrix.sanitizers }}"
 
   linux-shared-libs:
-    runs-on: ubuntu-latest
+    runs-on: ubuntu-20.04 # latest
     steps:
       # We can't use the `uses: docker://image` version yet, GitHub lacks authentication for actions -> packages
       - name: Build ${{ env.PACKAGE_NAME }}
@@ -83,7 +83,7 @@ jobs:
           ./linux-container-ci.sh ${{ env.BUILDER_VERSION }} aws-crt-${{ env.LINUX_BASE_IMAGE }} build -p ${{ env.PACKAGE_NAME }} --cmake-extra=-DBUILD_SHARED_LIBS=ON
 
   windows:
-    runs-on: windows-latest
+    runs-on: windows-2022 # latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
@@ -91,7 +91,7 @@ jobs:
         python builder.pyz build -p ${{ env.PACKAGE_NAME }}
 
   windows-vc14:
-    runs-on: windows-latest
+    runs-on: windows-2019 # windows-2019 is last env with Visual Studio 2015 (v14.0)
     strategy:
       matrix:
         arch: [x86, x64]
@@ -102,7 +102,7 @@ jobs:
         python builder.pyz build -p ${{ env.PACKAGE_NAME }} --target windows-${{ matrix.arch }} --compiler msvc-14
 
   windows-shared-libs:
-    runs-on: windows-latest
+    runs-on: windows-2022 # latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
@@ -110,7 +110,7 @@ jobs:
         python builder.pyz build -p ${{ env.PACKAGE_NAME }} --cmake-extra=-DBUILD_SHARED_LIBS=ON
 
   osx:
-    runs-on: macos-latest
+    runs-on: macos-11 # latest
     steps:
     - name: Build ${{ env.PACKAGE_NAME }} + consumers
       run: |
diff --git a/source/sdkutils.c b/source/sdkutils.c
index 8ae93f1..666e74f 100644
--- a/source/sdkutils.c
+++ b/source/sdkutils.c
@@ -31,7 +31,13 @@ static struct aws_log_subject_info_list s_sdkutils_log_subjects = {
     .count = AWS_ARRAY_SIZE(s_log_subject_infos),
 };
 
+static int s_library_init_count = 0;
+
 void aws_sdkutils_library_init(struct aws_allocator *allocator) {
+    if (s_library_init_count++ != 0) {
+        return;
+    }
+
     aws_common_library_init(allocator);
 
     aws_register_error_info(&s_sdkutils_error_info);
@@ -39,6 +45,10 @@ void aws_sdkutils_library_init(struct aws_allocator *allocator) {
 }
 
 void aws_sdkutils_library_clean_up(void) {
+    if (--s_library_init_count != 0) {
+        return;
+    }
+
     aws_unregister_log_subject_info_list(&s_sdkutils_log_subjects);
     aws_unregister_error_info(&s_sdkutils_error_info);