diff --git a/cmake/Assertion.cmake b/cmake/Assertion.cmake
index 7855586..1f3d34a 100644
--- a/cmake/Assertion.cmake
+++ b/cmake/Assertion.cmake
@@ -294,13 +294,6 @@ endmacro()
 #   - ARG2: The third argument.
 #   - ARG3: The fourth argument.
 macro(_assert_internal_assert_4 ARG0 ARG1 ARG2 ARG3)
-  if("${ARG0}" STREQUAL NOT)
-    _assert_internal_assert_3_not("${ARG1}" "${ARG2}" "${ARG3}")
-  else()
-    _assert_internal_format_message(
-      MESSAGE "unsupported condition:" "${ARG0} ${ARG1} ${ARG2} ${ARG3}")
-    message(FATAL_ERROR "${MESSAGE}")
-  endif()
 endmacro()
 
 # Asserts the given condition.
@@ -320,7 +313,13 @@ function(assert)
   elseif(ARGC EQUAL 3)
     _assert_internal_assert_3("${ARGV0}" "${ARGV1}" "${ARGV2}")
   elseif(ARGC EQUAL 4)
-    _assert_internal_assert_4("${ARGV0}" "${ARGV1}" "${ARGV2}" "${ARGV3}")
+    if("${ARGV0}" STREQUAL NOT)
+      _assert_internal_assert_3_not("${ARGV1}" "${ARGV2}" "${ARGV3}")
+    else()
+      _assert_internal_format_message(
+        MESSAGE "unsupported condition:" "${ARGV0} ${ARGV1} ${ARGV2} ${ARGV3}")
+      message(FATAL_ERROR "${MESSAGE}")
+    endif()
   else()
     set(ARGS "${ARGV0} ${ARGV1} ${ARGV2} ${ARGV3}")
     math(EXPR STOP "${ARGC} - 1")