diff --git a/acinclude.m4 b/acinclude.m4
index b65aeaa5..342968ea 100644
--- a/acinclude.m4
+++ b/acinclude.m4
@@ -269,7 +269,7 @@ AC_DEFUN([CURL_CC_DEBUG_OPTS],
           dnl Only clang 2.9 or later
           if test "$compiler_num" -ge "209"; then
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [sign-conversion])
-            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"
+            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"           # FIXME
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [shift-sign-overflow])
           # CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [padded])  # Not used because we cannot change public structs
           fi
@@ -459,7 +459,7 @@ AC_DEFUN([CURL_CC_DEBUG_OPTS],
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [clobbered ignored-qualifiers])
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [conversion trampolines])
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [sign-conversion])
-            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"
+            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"          # FIXME
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [vla])
             dnl required for -Warray-bounds, included in -Wall
             tmp_CFLAGS="$tmp_CFLAGS -ftree-vrp"
diff --git a/cmake/PickyWarnings.cmake b/cmake/PickyWarnings.cmake
index 6999cd83..a0a71edd 100644
--- a/cmake/PickyWarnings.cmake
+++ b/cmake/PickyWarnings.cmake
@@ -103,7 +103,7 @@ elseif(CMAKE_COMPILER_IS_GNUCC OR CMAKE_COMPILER_IS_GNUCXX OR CMAKE_C_COMPILER_I
       -Wold-style-definition               # clang  2.7  gcc  3.4
       -Wredundant-decls                    # clang  2.7  gcc  4.1
       -Wsign-conversion                    # clang  2.9  gcc  4.3
-        -Wno-error=sign-conversion
+        -Wno-error=sign-conversion                                              # FIXME
       -Wstrict-prototypes                  # clang  1.0  gcc  3.3
     # -Wswitch-enum                        # clang  2.7  gcc  4.1               # Not used because this basically disallows default case
       -Wtype-limits                        # clang  2.7  gcc  4.3