diff --git a/Makefile.am b/Makefile.am
index f8f3d7e8c9..b6dfbb6b5a 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -931,6 +931,7 @@ libnm_core_libnm_core_la_CPPFLAGS = \
 
 if WITH_JSON_VALIDATION
 libnm_core_libnm_core_la_CPPFLAGS += $(JANSSON_CFLAGS)
+libnm_core_libnm_core_la_CFLAGS = -fcommon
 endif
 
 libnm_core_libnm_core_la_SOURCES = \
diff --git a/libnm-core/meson.build b/libnm-core/meson.build
index bc2d087a15..e9e681d4fb 100644
--- a/libnm-core/meson.build
+++ b/libnm-core/meson.build
@@ -197,9 +197,12 @@ cflags = [
   '-DNETWORKMANAGER_COMPILATION=NM_NETWORKMANAGER_COMPILATION_LIBNM_CORE',
 ]
 
+libnm_core_c_args = cflags
+
 if enable_json_validation
   libnm_core_sources += files('nm-json.c')
   deps += jansson_dep
+  libnm_core_c_args += ['-fcommon']
 endif
 
 if (crypto_gnutls_dep.found())
@@ -237,8 +240,8 @@ libnm_core = static_library(
   'nm-core',
   sources: libnm_core_sources_all,
   dependencies: deps,
+  c_args: libnm_core_c_args,
   link_with: libnm_crypto,
-  c_args: cflags,
 )
 
 libnm_core_dep = declare_dependency(