diff --git a/configure.ac b/configure.ac
index e84005edf4bcf..1ed991afa7714 100644
--- a/configure.ac
+++ b/configure.ac
@@ -82,6 +82,15 @@ AC_COMPILE_IFELSE([AC_LANG_SOURCE([[char foo;]])],
       CFLAGS="$saved_CFLAGS"
     ])
 
+saved_CFLAGS="$CFLAGS"
+CFLAGS="-Wconditional-uninitialized $CFLAGS"
+AC_MSG_CHECKING([if ${CC} supports -Wconditional-uninitialized])
+AC_COMPILE_IFELSE([AC_LANG_SOURCE([[char foo;]])],
+    [ AC_MSG_RESULT([yes]) ],
+    [ AC_MSG_RESULT([no])
+      CFLAGS="$saved_CFLAGS"
+    ])
+
 saved_CFLAGS="$CFLAGS"
 CFLAGS="-fvisibility=hidden $CFLAGS"
 AC_MSG_CHECKING([if ${CC} supports -fvisibility=hidden])
diff --git a/src/tests.c b/src/tests.c
index e0c8c85605a3d..f19ab96e386a3 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -4526,8 +4526,10 @@ void test_ecdsa_sign_verify(void) {
     secp256k1_scalar one;
     secp256k1_scalar msg, key;
     secp256k1_scalar sigr, sigs;
-    int recid;
     int getrec;
+    /* Initialize recid to suppress a false positive -Wconditional-uninitialized in clang.
+       VG_UNDEF ensures that valgrind will still treat the variable as uninitialized. */
+    int recid = -1; VG_UNDEF(&recid, sizeof(recid));
     random_scalar_order_test(&msg);
     random_scalar_order_test(&key);
     secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &pubj, &key);