diff --git a/CMake/PickyWarnings.cmake b/CMake/PickyWarnings.cmake
index aca79ec947..24d99d6332 100644
--- a/CMake/PickyWarnings.cmake
+++ b/CMake/PickyWarnings.cmake
@@ -130,12 +130,13 @@ if(PICKY_COMPILER)
       -Wmissing-field-initializers         # clang  2.7  gcc  4.1
       -Wmissing-noreturn                   # clang  2.7  gcc  4.1
       -Wno-padded                          # clang  2.9  gcc  4.1               # Not used: We cannot change public structs
-      -Wno-sign-conversion                 # clang  2.9  gcc  4.3
       -Wno-switch-default                  # clang  2.7  gcc  4.1               # Not used: Annoying to fix or silence
       -Wno-switch-enum                     # clang  2.7  gcc  4.1               # Not used: It basically disallows default case
       -Wno-system-headers                  # clang  1.0  gcc  3.0
       -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
       -Wstrict-prototypes                  # clang  1.0  gcc  3.3
       -Wtype-limits                        # clang  2.7  gcc  4.3
       -Wunreachable-code                   # clang  2.7  gcc  4.1
@@ -331,6 +332,7 @@ if(PICKY_COMPILER)
       if(CMAKE_C_COMPILER_VERSION VERSION_GREATER_EQUAL 10.0)
         list(APPEND _picky_enable
           -Warith-conversion               #             gcc 10.0
+            -Wno-error=arith-conversion    #             gcc 10.0                             # extra hits with -Wsign-conversion
           -Wenum-conversion                # clang  3.2  gcc 10.0  appleclang  4.2  g++ 11.0
         )
       endif()
diff --git a/m4/curl-compilers.m4 b/m4/curl-compilers.m4
index 4bb7196eae..5c50d41938 100644
--- a/m4/curl-compilers.m4
+++ b/m4/curl-compilers.m4
@@ -851,7 +851,8 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
 
           dnl Only clang 2.9 or later
           if test "$compiler_num" -ge "209"; then
-            tmp_CFLAGS="$tmp_CFLAGS -Wno-sign-conversion"
+            CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [sign-conversion])
+            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"
             tmp_CFLAGS="$tmp_CFLAGS -Wno-padded"                         # Not used because we cannot change public structs
             tmp_CFLAGS="$tmp_CFLAGS -Wno-used-but-marked-unused"         # for typecheck-gcc.h with clang 14+, dependency headers
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [shift-sign-overflow])
@@ -1099,7 +1100,8 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [missing-parameter-type empty-body])
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [clobbered ignored-qualifiers])
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [conversion])
-            tmp_CFLAGS="$tmp_CFLAGS -Wno-sign-conversion"
+            CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [sign-conversion])
+            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=sign-conversion"
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [vla])
             dnl required for -Warray-bounds, included in -Wall
             tmp_CFLAGS="$tmp_CFLAGS -ftree-vrp"
@@ -1159,6 +1161,7 @@ AC_DEFUN([CURL_SET_COMPILER_WARNING_OPTS], [
           dnl Only gcc 10 or later
           if test "$compiler_num" -ge "1000"; then
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [arith-conversion])
+            tmp_CFLAGS="$tmp_CFLAGS -Wno-error=arith-conversion"  # extra hits with -Wsign-conversion
             CURL_ADD_COMPILER_WARNINGS([tmp_CFLAGS], [enum-conversion])
           fi