diff --git a/develop/singles/headers/meta.hpp/meta_all.hpp b/develop/singles/headers/meta.hpp/meta_all.hpp
index 41a4a14..24de960 100644
--- a/develop/singles/headers/meta.hpp/meta_all.hpp
+++ b/develop/singles/headers/meta.hpp/meta_all.hpp
@@ -20,13 +20,10 @@
 #include <mutex>
 #include <set>
 #include <span>
-#include <stdexcept>
 #include <string>
 #include <string_view>
 #include <tuple>
 #include <type_traits>
-#include <typeindex>
-#include <typeinfo>
 #include <utility>
 #include <variant>
 #include <vector>
@@ -40,9 +37,12 @@
 #endif
 
 #if !defined(META_HPP_NO_EXCEPTIONS)
+#  include <stdexcept>
 #endif
 
 #if !defined(META_HPP_NO_RTTI)
+#  include <typeindex>
+#  include <typeinfo>
 #endif
 
 namespace meta_hpp::detail
diff --git a/develop/singles/scripts/build_singles.py b/develop/singles/scripts/build_singles.py
index e406e66..b3af5f8 100755
--- a/develop/singles/scripts/build_singles.py
+++ b/develop/singles/scripts/build_singles.py
@@ -12,6 +12,9 @@ import sys
 EMPTY_MATCHER = re.compile(r'^\s*$')
 C_COMMENT_MATCHER = re.compile(r'^/\*.*\*/', re.S)
 
+IFDEF_MATCHER = re.compile(r'#\s*if')
+ENDDEF_MATCHER = re.compile(r'#\s*endif')
+
 USER_INCLUDE_MATCHER = re.compile(r'#\s*include\s*\"(.*)\"')
 SYSTEM_INCLUDE_MATCHER = re.compile(r'#\s*include\s*<(.*)>')
 PRAGMA_ONCE_MATCHER = re.compile(r'#\s*pragma\s+once')
@@ -33,18 +36,25 @@ def CollectSystemIncludes(headerPath, parsedHeaders = set()):
         if PRAGMA_ONCE_MATCHER.search(headerContent) and headerPath in parsedHeaders:
             return set()
 
+        ifdefScopeLevel = 0
         headerIncludes = set()
 
         parsedHeaders.add(headerPath)
         headerLines = headerContent.split('\n')
 
         for headerLine in headerLines:
+            if IFDEF_MATCHER.match(headerLine):
+                ifdefScopeLevel += 1
+            elif ENDDEF_MATCHER.match(headerLine):
+                ifdefScopeLevel -= 1
+
             includeMatch = USER_INCLUDE_MATCHER.findall(headerLine)
-            if includeMatch:
+            if includeMatch and ifdefScopeLevel == 0:
                 internalHeaderPath = os.path.abspath(os.path.join(os.path.dirname(headerPath), includeMatch[0]))
                 headerIncludes = headerIncludes.union(CollectSystemIncludes(internalHeaderPath, parsedHeaders))
+
             includeMatch = SYSTEM_INCLUDE_MATCHER.findall(headerLine)
-            if includeMatch:
+            if includeMatch and ifdefScopeLevel == 0:
                 headerIncludes.add(includeMatch[0])
 
         return headerIncludes
@@ -61,6 +71,7 @@ def ParseHeader(headerPath, parsedHeaders = set()):
         headerLines = headerContent.split('\n')
 
         outputContent = ""
+        ifdefScopeLevel = 0
         shouldSkipNextEmptyLines = True
 
         for headerLine in headerLines:
@@ -71,8 +82,13 @@ def ParseHeader(headerPath, parsedHeaders = set()):
                 shouldSkipNextEmptyLines = True
                 continue
 
+            if IFDEF_MATCHER.match(headerLine):
+                ifdefScopeLevel += 1
+            elif ENDDEF_MATCHER.match(headerLine):
+                ifdefScopeLevel -= 1
+
             includeMatch = USER_INCLUDE_MATCHER.findall(headerLine)
-            if includeMatch:
+            if includeMatch and ifdefScopeLevel == 0:
                 internalHeaderPath = os.path.abspath(os.path.join(os.path.dirname(headerPath), includeMatch[0]))
                 internalHeaderContent = ParseHeader(internalHeaderPath, parsedHeaders)
 
@@ -81,7 +97,7 @@ def ParseHeader(headerPath, parsedHeaders = set()):
                 continue
 
             includeMatch = SYSTEM_INCLUDE_MATCHER.findall(headerLine)
-            if includeMatch:
+            if includeMatch and ifdefScopeLevel == 0:
                 shouldSkipNextEmptyLines = True
                 continue