diff --git a/CMakeLists.txt b/CMakeLists.txt
index 76d9397a8..79d7922f3 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -660,6 +660,16 @@ SET (PBRT_UTIL_SOURCE
   src/pbrt/util/vecmath.cpp
 )
 
+# A warning about a deprecated function in C++17 but the solution will only be
+# in C++26.
+if (CMAKE_CXX_COMPILER_ID MATCHES "GNU|Clang")
+    set_source_files_properties(
+        src/pbrt/util/string.cpp
+        PROPERTIES
+        COMPILE_FLAGS "-Wno-deprecated-declarations"
+    )
+endif()
+
 SET (PBRT_UTIL_SOURCE_HEADERS
   src/pbrt/util/args.h
   src/pbrt/util/bluenoise.h