diff --git a/CMake/PickyWarnings.cmake b/CMake/PickyWarnings.cmake
index d1183fe392a4b8..3c96f3c33f0869 100644
--- a/CMake/PickyWarnings.cmake
+++ b/CMake/PickyWarnings.cmake
@@ -98,7 +98,6 @@ if(PICKY_COMPILER)
       -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                                              # 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
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 9a4547709eb1cd..8feb4c5064d9b7 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -831,7 +831,6 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_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"          # 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
@@ -1023,7 +1022,6 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_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="$tmp_CFLAGS -Wno-error=sign-conversion"          # FIXME
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [vla])
             dnl required for -Warray-bounds, included in -Wall
             tmp_CFLAGS="$tmp_CFLAGS -ftree-vrp"