diff --git a/build_detect_platform b/build_detect_platform
index 0768429..82d73a6 100755
--- a/build_detect_platform
+++ b/build_detect_platform
@@ -200,6 +200,8 @@ EOF
     if [ "$?" = 0 ]; then
         COMMON_FLAGS="$COMMON_FLAGS -DHAVE_CRC32C=1"
         PLATFORM_LIBS="$PLATFORM_LIBS -lcrc32c"
+    else
+        COMMON_FLAGS="$COMMON_FLAGS -DHAVE_CRC32C=0"
     fi
 
     # Test whether Snappy library is installed
@@ -211,6 +213,8 @@ EOF
     if [ "$?" = 0 ]; then
         COMMON_FLAGS="$COMMON_FLAGS -DHAVE_SNAPPY=1"
         PLATFORM_LIBS="$PLATFORM_LIBS -lsnappy"
+    else
+        COMMON_FLAGS="$COMMON_FLAGS -DHAVE_SNAPPY=0"
     fi
 
     # Test whether tcmalloc is available
diff --git a/port/port_posix.h b/port/port_posix.h
index d30f0f2..5bfc12e 100644
--- a/port/port_posix.h
+++ b/port/port_posix.h
@@ -39,12 +39,12 @@
 #endif
 
 #include <pthread.h>
-#if defined(HAVE_CRC32C)
+#if HAVE_CRC32C
 #include <crc32c/crc32c.h>
-#endif  // defined(HAVE_CRC32C)
-#ifdef HAVE_SNAPPY
+#endif  // HAVE_CRC32C
+#if HAVE_SNAPPY
 #include <snappy.h>
-#endif  // defined(HAVE_SNAPPY)
+#endif  // HAVE_SNAPPY
 #include <stdint.h>
 #include <string>
 #include "port/atomic_pointer.h"
@@ -110,33 +110,33 @@ extern void InitOnce(OnceType* once, void (*initializer)());
 
 inline bool Snappy_Compress(const char* input, size_t length,
                             ::std::string* output) {
-#ifdef HAVE_SNAPPY
+#if HAVE_SNAPPY
   output->resize(snappy::MaxCompressedLength(length));
   size_t outlen;
   snappy::RawCompress(input, length, &(*output)[0], &outlen);
   output->resize(outlen);
   return true;
-#endif  // defined(HAVE_SNAPPY)
+#endif  // HAVE_SNAPPY
 
   return false;
 }
 
 inline bool Snappy_GetUncompressedLength(const char* input, size_t length,
                                          size_t* result) {
-#ifdef HAVE_SNAPPY
+#if HAVE_SNAPPY
   return snappy::GetUncompressedLength(input, length, result);
 #else
   return false;
-#endif  // defined(HAVE_SNAPPY)
+#endif  // HAVE_SNAPPY
 }
 
 inline bool Snappy_Uncompress(const char* input, size_t length,
                               char* output) {
-#ifdef HAVE_SNAPPY
+#if HAVE_SNAPPY
   return snappy::RawUncompress(input, length, output);
 #else
   return false;
-#endif  // defined(HAVE_SNAPPY)
+#endif  // HAVE_SNAPPY
 }
 
 inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
@@ -144,11 +144,11 @@ inline bool GetHeapProfile(void (*func)(void*, const char*, int), void* arg) {
 }
 
 inline uint32_t AcceleratedCRC32C(uint32_t crc, const char* buf, size_t size) {
-#if defined(HAVE_CRC32C)
+#if HAVE_CRC32C
   return ::crc32c::Extend(crc, reinterpret_cast<const uint8_t*>(buf), size);
 #else
   return 0;
-#endif  // defined(HAVE_CRC32C)
+#endif  // HAVE_CRC32C
 }
 
 }  // namespace port