diff --git a/var/spack/repos/builtin/packages/hdf/package.py b/var/spack/repos/builtin/packages/hdf/package.py
index d087ea05ec8..ab929bed606 100644
--- a/var/spack/repos/builtin/packages/hdf/package.py
+++ b/var/spack/repos/builtin/packages/hdf/package.py
@@ -144,6 +144,14 @@ def flag_handler(self, name, flags):
             elif name == "fflags":
                 flags.append(self.compiler.f77_pic_flag)
 
+        if name == "cflags":
+            # https://forum.hdfgroup.org/t/help-building-hdf4-with-clang-error-implicit-declaration-of-function-test-mgr-szip-is-invalid-in-c99/7680
+            if self.spec.satisfies("@:4.2.15 %apple-clang") or self.spec.satisfies("%clang@16:"):
+                flags.append("-Wno-error=implicit-function-declaration")
+
+            if self.spec.satisfies("%clang@16:"):
+                flags.append("-Wno-error=implicit-int")
+
         return flags, None, None
 
     def configure_args(self):
@@ -178,10 +186,6 @@ def configure_args(self):
                 ["FFLAGS=-fallow-argument-mismatch", "FCFLAGS=-fallow-argument-mismatch"]
             )
 
-        # https://forum.hdfgroup.org/t/help-building-hdf4-with-clang-error-implicit-declaration-of-function-test-mgr-szip-is-invalid-in-c99/7680
-        if self.spec.satisfies("@:4.2.15 %apple-clang"):
-            config_args.append("CFLAGS=-Wno-error=implicit-function-declaration")
-
         return config_args
 
     # Otherwise, we randomly get: