--- a/absl/base/internal/direct_mmap.h
+++ b/absl/base/internal/direct_mmap.h
@@ -20,7 +20,7 @@
 
 #include "absl/base/config.h"
 
-#if ABSL_HAVE_MMAP
+#ifdef ABSL_HAVE_MMAP
 
 #include <sys/mman.h>
 
@@ -35,6 +35,7 @@
 
 #include <linux/unistd.h>
 #include <unistd.h>
+
 #include <cerrno>
 #include <cstdarg>
 #include <cstdint>
--- a/absl/time/internal/cctz/src/time_zone_format.cc
+++ b/absl/time/internal/cctz/src/time_zone_format.cc
@@ -40,7 +40,7 @@
 #include <limits>
 #include <string>
 #include <vector>
-#if !HAS_STRPTIME
+#if !defined(HAS_STRPTIME)
 #include <iomanip>
 #include <sstream>
 #endif
@@ -56,7 +56,7 @@ namespace detail {
 
 namespace {
 
-#if !HAS_STRPTIME
+#if !defined(HAS_STRPTIME)
 // Build a strptime() using C++11's std::get_time().
 char* strptime(const char* s, const char* fmt, std::tm* tm) {
   std::istringstream input(s);
--- a/absl/base/internal/sysinfo.cc
+++ b/absl/base/internal/sysinfo.cc
@@ -81,7 +81,11 @@ static double GetNominalCPUFrequency() {
   // API informing about CPU nominal frequency.
   return 1.0;
 #else
+
+#if defined(_MSC_VER)
 #pragma comment(lib, "advapi32.lib")  // For Reg* functions.
+#endif
+
   HKEY key;
   // Use the Reg* functions rather than the SH functions because shlwapi.dll
   // pulls in gdi32.dll which makes process destruction much more costly.
--- a/absl/debugging/symbolize_win32.inc
+++ b/absl/debugging/symbolize_win32.inc
@@ -18,12 +18,16 @@
 #include <windows.h>
 
 // MSVC header dbghelp.h has a warning for an ignored typedef.
+#ifdef _MSC_VER
 #pragma warning(push)
 #pragma warning(disable:4091)
 #include <dbghelp.h>
 #pragma warning(pop)
 
 #pragma comment(lib, "dbghelp.lib")
+#else
+#include <dbghelp.h>
+#endif
 
 #include <algorithm>
 #include <cstring>
--- a/absl/random/internal/randen_detect.cc
+++ b/absl/random/internal/randen_detect.cc
@@ -40,7 +40,9 @@
 #if defined(ABSL_INTERNAL_USE_X86_CPUID)
 #if defined(_WIN32) || defined(_WIN64)
 #include <intrin.h>  // NOLINT(build/include_order)
+#if defined(_MSC_VER)
 #pragma intrinsic(__cpuid)
+#endif
 #else
 // MSVC-equivalent __cpuid intrinsic function.
 static void __cpuid(int cpu_info[4], int info_type) {
--- a/absl/random/internal/seed_material.cc
+++ b/absl/random/internal/seed_material.cc
@@ -43,7 +43,10 @@
 
 #include <windows.h>
 #define ABSL_RANDOM_USE_BCRYPT 1
+
+#ifdef _MSC_VER
 #pragma comment(lib, "bcrypt.lib")
+#endif
 
 #elif defined(__Fuchsia__)
 #include <zircon/syscalls.h>