diff --git a/cmake/Modules/DefineCompilerFlags.cmake b/cmake/Modules/DefineCompilerFlags.cmake
index 7b65720..4fb0aed 100644
--- a/cmake/Modules/DefineCompilerFlags.cmake
+++ b/cmake/Modules/DefineCompilerFlags.cmake
@@ -13,7 +13,7 @@
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu99 -pedantic -pedantic-errors")
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wall -Wextra -Wshadow -Wmissing-prototypes -Wdeclaration-after-statement")
         set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wunused -Wfloat-equal -Wpointer-arith -Wwrite-strings -Wformat-security")
-        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-format-attribute")
+        set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -Wmissing-format-attribute -Wundef")
 
         # with -fPIC
         check_c_compiler_flag("-fPIC" WITH_FPIC)
diff --git a/doc/index.html b/doc/index.html
index 8db0247..5f7c5a7 100644
--- a/doc/index.html
+++ b/doc/index.html
@@ -137,7 +137,7 @@
 #include &lt;assert.h&gt;
 
 // If unit testing is enabled override assert with mock_assert().
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 extern void mock_assert(const int result, const char* const expression, 
                         const char * const file, const int line);
 #undef assert
@@ -285,7 +285,7 @@
 <listing>
 #include &lt;malloc.h&gt;
 
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 extern void* _test_malloc(const size_t size, const char* file, const int line);
 extern void* _test_calloc(const size_t number_of_elements, const size_t size, 
                           const char* file, const int line);
diff --git a/example/allocate_module.c b/example/allocate_module.c
index 295e10e..3c4fb49 100644
--- a/example/allocate_module.c
+++ b/example/allocate_module.c
@@ -22,7 +22,7 @@
 #include <sys/types.h>
 #include <stdlib.h>
 
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 extern void* _test_malloc(const size_t size, const char* file, const int line);
 extern void* _test_calloc(const size_t number_of_elements, const size_t size,
                           const char* file, const int line);
diff --git a/example/assert_module.c b/example/assert_module.c
index bb75aaa..381069b 100644
--- a/example/assert_module.c
+++ b/example/assert_module.c
@@ -18,7 +18,7 @@
 #include "assert_module.h"
 
 /* If unit testing is enabled override assert with mock_assert(). */
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 extern void mock_assert(const int result, const char* const expression,
                         const char * const file, const int line);
 #undef assert
diff --git a/example/calculator.c b/example/calculator.c
index 684fb9b..307b551 100644
--- a/example/calculator.c
+++ b/example/calculator.c
@@ -28,7 +28,7 @@
 #include <string.h>
 
 /* If this is being built for a unit test. */
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 
 /* Redirect printf to a function in the test application so it's possible to
  * test the standard output. */
diff --git a/include/cmocka.h b/include/cmocka.h
index a3544b7..0047df9 100644
--- a/include/cmocka.h
+++ b/include/cmocka.h
@@ -384,7 +384,7 @@
                   cast_to_largest_integral_type(check_data), NULL, 0)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is part of the provided
  *        array.
@@ -405,7 +405,7 @@
     expect_in_set_count(function, parameter, value_array, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is part of the provided
  *        array.
@@ -431,7 +431,7 @@
                    sizeof(value_array) / sizeof((value_array)[0]), count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is not part of the
  *        provided array.
@@ -452,7 +452,7 @@
     expect_not_in_set_count(function, parameter, value_array, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is not part of the
  *        provided array.
@@ -480,7 +480,7 @@
 #endif
 
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check a parameter is inside a numerical range.
  * The check would succeed if minimum <= value <= maximum.
@@ -503,7 +503,7 @@
     expect_in_range_count(function, parameter, minimum, maximum, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check a parameter is inside a
  * numerical range. The check would succeed if minimum <= value <= maximum.
@@ -531,7 +531,7 @@
                      maximum, count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check a parameter is outside a numerical range.
  * The check would succeed if minimum > value > maximum.
@@ -554,7 +554,7 @@
     expect_not_in_range_count(function, parameter, minimum, maximum, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check a parameter is outside a
  * numerical range. The check would succeed if minimum > value > maximum.
@@ -583,7 +583,7 @@
                          minimum, maximum, count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if a parameter is the given value.
  *
@@ -603,7 +603,7 @@
     expect_value_count(function, parameter, value, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check if a parameter is the given value.
  *
@@ -628,7 +628,7 @@
                   cast_to_largest_integral_type(value), count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if a parameter isn't the given value.
  *
@@ -648,7 +648,7 @@
     expect_not_value_count(function, parameter, value, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check if a parameter isn't the given value.
  *
@@ -673,7 +673,7 @@
                       cast_to_largest_integral_type(value), count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is equal to the
  *        provided string.
@@ -694,7 +694,7 @@
     expect_string_count(function, parameter, string, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value is equal to the
  *        provided string.
@@ -720,7 +720,7 @@
                    (const char*)(string), count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value isn't equal to the
  *        provided string.
@@ -741,7 +741,7 @@
     expect_not_string_count(function, parameter, string, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter value isn't equal to the
  *        provided string.
@@ -767,7 +767,7 @@
                        (const char*)(string), count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter does match an area of memory.
  *
@@ -789,7 +789,7 @@
     expect_memory_count(function, parameter, memory, size, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check if the parameter does match an area
  *        of memory.
@@ -817,7 +817,7 @@
                    (const void*)(memory), size, count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if the parameter doesn't match an area of
  *        memory.
@@ -840,7 +840,7 @@
     expect_not_memory_count(function, parameter, memory, size, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check if the parameter doesn't match an
  *        area of memory.
@@ -869,7 +869,7 @@
 #endif
 
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to check if a parameter (of any value) has been passed.
  *
@@ -887,7 +887,7 @@
     expect_any_count(function, parameter, 1)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Add an event to repeatedly check if a parameter (of any value) has
  *        been passed.
@@ -910,7 +910,7 @@
     _expect_any(#function, #parameter, __FILE__, __LINE__, count)
 #endif
 
-#if DOXYGEN
+#ifdef DOXYGEN
 /**
  * @brief Determine whether a function parameter is correct.
  *
@@ -1431,7 +1431,7 @@
  * @return A pointer to the allocated memory or NULL on error.
  *
  * @code
- * #if UNIT_TESTING
+ * #ifdef UNIT_TESTING
  * extern void* _test_malloc(const size_t size, const char* file, const int line);
  *
  * #define malloc(size) _test_malloc(size, __FILE__, __LINE__)
@@ -1483,7 +1483,7 @@
 #endif
 
 /* Redirect malloc, calloc and free to the unit test allocators. */
-#if UNIT_TESTING
+#ifdef UNIT_TESTING
 #define malloc test_malloc
 #define calloc test_calloc
 #define free test_free
@@ -1524,7 +1524,7 @@
  * @param[in]  line  The line mock_assert() is called.
  *
  * @code
- * #if UNIT_TESTING
+ * #ifdef UNIT_TESTING
  * extern void mock_assert(const int result, const char* const expression,
  *                         const char * const file, const int line);
  *
diff --git a/src/cmocka.c b/src/cmocka.c
index b4de262..76cd783 100644
--- a/src/cmocka.c
+++ b/src/cmocka.c
@@ -1697,7 +1697,7 @@
 #ifdef _WIN32
     handle_exceptions = !IsDebuggerPresent();
 #endif /* _WIN32 */
-#if UNIT_TESTING_DEBUG
+#ifdef UNIT_TESTING_DEBUG
     handle_exceptions = 0;
 #endif /* UNIT_TESTING_DEBUG */