diff --git a/CTestCustom.cmake.in b/CTestCustom.cmake.in
index 49026a33d1..cb6b485906 100644
--- a/CTestCustom.cmake.in
+++ b/CTestCustom.cmake.in
@@ -83,6 +83,11 @@ list(APPEND CTEST_CUSTOM_WARNING_EXCEPTION
   "compilation completed with warnings" # PGI
   "[0-9]+ Warning\\(s\\) detected" # SunPro
 
+  # Ignore false positive on `cm::optional` usage from GCC
+  "cmGlobalNinjaGenerator.cxx:[0-9]*:[0-9]*: warning: '.*cm::optional<CxxModuleMapFormat>::_mem\\)\\)' may be used uninitialized \\[-Wmaybe-uninitialized\\]"
+  "cmGlobalNinjaGenerator.cxx:[0-9]*:[0-9]*: note: '.*cm::optional<CxxModuleMapFormat>::_mem\\)\\)' was declared here"
+  "cmGlobalNinjaGenerator.cxx:[0-9]*:[0-9]*: warning: '\\*\\(\\(void\\*\\)& modmap_fmt \\+4\\)' may be used uninitialized in this function \\[-Wmaybe-uninitialized\\]"
+
   # clang-analyzer exceptions
   "cmListFileLexer.c:[0-9]+:[0-9]+: warning: Array subscript is undefined"
   "jsoncpp/src/.*:[0-9]+:[0-9]+: warning: Value stored to .* is never read"