diff --git a/.cirrus.yml b/.cirrus.yml
index c3799ca..cf7fc17 100644
--- a/.cirrus.yml
+++ b/.cirrus.yml
@@ -1,5 +1,5 @@
 freebsd_instance:
-  image_family: freebsd-13-0
+  image_family: freebsd-15
 
 task:
   install_script: pkg install -y cmake
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index d33f9ec..84e398a 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -45,7 +45,7 @@ jobs:
           EOF
 
       - name: Compile Test Amalgamation
-        run: gcc -Wall -Wextra -Werror -o test_amalg test_amalg.c
+        run: gcc -std=c89 -Wpedantic -Wall -Wextra -Werror -o test_amalg test_amalg.c
 
       - name: Run Test Amalgamation
         run: ./test_amalg
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 07bcffa..62c2476 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,11 +1,45 @@
 cmake_minimum_required(VERSION 3.11)
 project(c89stringutils VERSION 0.0.2 LANGUAGES C)
 
+include(CheckCSourceCompiles)
+
+check_c_source_compiles("#include <stdarg.h>
+    void t(int i, ...) { va_list a, b; va_start(a,i); va_copy(b,a); va_end(b); va_end(a); }
+    int main() { return 0; }" HAVE_VA_COPY)
+
+check_c_source_compiles("#include <stdarg.h>
+    void t(int i, ...) { va_list a, b; va_start(a,i); __va_copy(b,a); va_end(b); va_end(a); }
+    int main() { return 0; }" HAVE___VA_COPY)
+
+check_c_source_compiles("#include <stdarg.h>
+    void t(int i, ...) { va_list a, b; va_start(a,i); b = a; va_end(a); }
+    int main() { return 0; }" HAVE_VA_LIST_ASSIGNMENT)
+
+check_c_source_compiles("
+int main(void) {
+  long long x = 0;
+  return (int)x;
+}
+" HAVE_LONG_LONG)
+
 set(CMAKE_C_VISIBILITY_PRESET hidden)
 set(CMAKE_VISIBILITY_INLINES_HIDDEN YES)
 set(CMAKE_C_STANDARD 90)
 
 add_library("${PROJECT_NAME}_compiler_flags" INTERFACE)
+
+if(HAVE_VA_COPY)
+    target_compile_definitions("${PROJECT_NAME}_compiler_flags" INTERFACE HAVE_VA_COPY)
+elseif(HAVE___VA_COPY)
+    target_compile_definitions("${PROJECT_NAME}_compiler_flags" INTERFACE HAVE___VA_COPY)
+elseif(HAVE_VA_LIST_ASSIGNMENT)
+    target_compile_definitions("${PROJECT_NAME}_compiler_flags" INTERFACE HAVE_VA_LIST_ASSIGNMENT)
+endif()
+
+if(HAVE_LONG_LONG)
+    target_compile_definitions("${PROJECT_NAME}_compiler_flags" INTERFACE HAVE_LONG_LONG)
+endif()
+
 if (NOT DEFINED MSVC_VERSION
         OR MSVC_VERSION STRGREATER "1900" # 2015
         OR NOT (CMAKE_C_COMPILER_ID STREQUAL "OpenWatcom"))
diff --git a/c89stringutils/CMakeLists.txt b/c89stringutils/CMakeLists.txt
index 8e0bcac..e4647e9 100644
--- a/c89stringutils/CMakeLists.txt
+++ b/c89stringutils/CMakeLists.txt
@@ -8,6 +8,8 @@ source_group("Source Files" FILES "${Source_Files}")
 
 add_library("${LIBRARY_NAME}" "${Header_Files}" "${Source_Files}")
 
+target_link_libraries("${LIBRARY_NAME}" PUBLIC "${PROJECT_NAME}_compiler_flags")
+
 include(GNUInstallDirs)
 target_include_directories(
         "${LIBRARY_NAME}"
diff --git a/c89stringutils/c89stringutils_string_extras.c b/c89stringutils/c89stringutils_string_extras.c
index 5ed8c41..2fb7a32 100644
--- a/c89stringutils/c89stringutils_string_extras.c
+++ b/c89stringutils/c89stringutils_string_extras.c
@@ -92,22 +92,69 @@ static int wtf_vsnprintf(char *buffer, size_t count, const char *format,
 #define HAVE_STRNCASECMP_H
 
 int strncasecmp(const char *s1, const char *s2, size_t n) {
-  int rc;
+  int rc = 0;
+  size_t i;
+  
   if (s1 == NULL || s2 == NULL) {
     LOG_DEBUG("s1 or s2 is NULL");
     return -1;
   }
-  rc = _strnicmp(s1, s2, n);
+  
+  for (i = 0; i < n && s1[i] && s2[i]; i++) {
+    char c1 = s1[i];
+    char c2 = s2[i];
+    
+    /* Convert to lowercase for comparison */
+    if (c1 >= 'A' && c1 <= 'Z') c1 += 'a' - 'A';
+    if (c2 >= 'A' && c2 <= 'Z') c2 += 'a' - 'A';
+    
+    if (c1 != c2) {
+      rc = (c1 < c2) ? -1 : 1;
+      break;
+    }
+  }
+  
+  /* Handle end of string cases */
+  if (rc == 0 && i < n) {
+    if (!s1[i] && !s2[i]) rc = 0;
+    else if (!s1[i]) rc = -1;
+    else rc = 1;
+  }
+  
   return rc;
 }
 
 int strcasecmp(const char *s1, const char *s2) {
-  int rc;
+  int rc = 0;
+  size_t i = 0;
+  
   if (s1 == NULL || s2 == NULL) {
     LOG_DEBUG("s1 or s2 is NULL");
     return -1;
   }
-  rc = _stricmp(s1, s2);
+  
+  while (s1[i] && s2[i]) {
+    char c1 = s1[i];
+    char c2 = s2[i];
+    
+    /* Convert to lowercase for comparison */
+    if (c1 >= 'A' && c1 <= 'Z') c1 += 'a' - 'A';
+    if (c2 >= 'A' && c2 <= 'Z') c2 += 'a' - 'A';
+    
+    if (c1 != c2) {
+      rc = (c1 < c2) ? -1 : 1;
+      break;
+    }
+    i++;
+  }
+  
+  /* Handle end of string cases */
+  if (rc == 0) {
+    if (!s1[i] && !s2[i]) rc = 0;
+    else if (!s1[i]) rc = -1;
+    else rc = 1;
+  }
+  
   return rc;
 }
 
@@ -175,6 +222,42 @@ size_t strerrorlen_s(errno_t errnum) {
 #define ESNULLP (400) /* null ptr                    */
 #endif
 
+#ifndef ESZEROL
+#define ESZEROL (401) /* length is zero            */
+#endif
+
+#ifndef ESLEMIN
+#define ESLEMIN (402) /* length is below min        */
+#endif
+
+#ifndef ESLEMAX
+#define ESLEMAX (403) /* length exceeds RSIZE_MAX   */
+#endif
+
+#ifndef ESOVRLP
+#define ESOVRLP (404) /* overlap undefined          */
+#endif
+
+#ifndef ESEMPTY
+#define ESEMPTY (405) /* empty string               */
+#endif
+
+#ifndef ESNOSPC
+#define ESNOSPC (406) /* not enough space           */
+#endif
+
+#ifndef ESUNTERM
+#define ESUNTERM (407) /* unterminated string        */
+#endif
+
+#ifndef ESNODIFF
+#define ESNODIFF (408) /* no difference              */
+#endif
+
+#ifndef ESNOTFND
+#define ESNOTFND (409) /* not found                  */
+#endif
+
 #ifndef ESLEWRNG
 #define ESLEWRNG (410) /* wrong size                */
 #endif
diff --git a/c89stringutils/c89stringutils_string_extras.h b/c89stringutils/c89stringutils_string_extras.h
index 159e059..ff4a6cc 100644
--- a/c89stringutils/c89stringutils_string_extras.h
+++ b/c89stringutils/c89stringutils_string_extras.h
@@ -19,7 +19,11 @@ extern "C" {
 #if defined(_MSC_VER)
 #define NUM_FORMAT "%I64d"
 #else
+#if defined(HAVE_LONG_LONG)
 #define NUM_FORMAT "%lld"
+#else
+#define NUM_FORMAT "%ld"
+#endif
 #endif
 
 #if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) ||     \
@@ -102,7 +106,6 @@ typedef int errno_t;
 
 #ifndef _MSC_VER
 #define HAVE_STRINGS_H
-#define HAVE_STRNCASECMP_H
 #endif
 
 #if !defined(HAVE_ASPRINTF) &&                                                 \
diff --git a/c89stringutils/tests/CMakeLists.txt b/c89stringutils/tests/CMakeLists.txt
index b5626d6..c447ffc 100644
--- a/c89stringutils/tests/CMakeLists.txt
+++ b/c89stringutils/tests/CMakeLists.txt
@@ -25,7 +25,7 @@ source_group("Source Files" FILES "${Source_Files}")
 
 add_executable("${EXEC_NAME}" "${Header_Files}" "${Source_Files}")
 
-target_link_libraries("${EXEC_NAME}" PRIVATE "${PROJECT_NAME}")
+target_link_libraries("${EXEC_NAME}" PRIVATE c89stringutils)
 if (NOT CMAKE_C_COMPILER_ID STREQUAL "OpenWatcom")
     target_link_libraries("${EXEC_NAME}" PRIVATE "${PROJECT_NAME}_compiler_flags")
 endif (NOT CMAKE_C_COMPILER_ID STREQUAL "OpenWatcom")