diff --git a/src/core/devices/wwan/nm-modem-broadband.c b/src/core/devices/wwan/nm-modem-broadband.c
index 775afa64e..81f090c61 100644
--- a/src/core/devices/wwan/nm-modem-broadband.c
+++ b/src/core/devices/wwan/nm-modem-broadband.c
@@ -204,6 +204,13 @@ get_capabilities(NMModem                   *_self,
     MMModemCapability *supported;
     guint              n_supported;
 
+    G_STATIC_ASSERT(MM_MODEM_CAPABILITY_POTS == (guint64) NM_DEVICE_MODEM_CAPABILITY_POTS);
+    G_STATIC_ASSERT(MM_MODEM_CAPABILITY_CDMA_EVDO
+                    == (guint64) NM_DEVICE_MODEM_CAPABILITY_CDMA_EVDO);
+    G_STATIC_ASSERT(MM_MODEM_CAPABILITY_GSM_UMTS == (guint64) NM_DEVICE_MODEM_CAPABILITY_GSM_UMTS);
+    G_STATIC_ASSERT(MM_MODEM_CAPABILITY_LTE == (guint64) NM_DEVICE_MODEM_CAPABILITY_LTE);
+    G_STATIC_ASSERT(MM_MODEM_CAPABILITY_5GNR == (guint64) NM_DEVICE_MODEM_CAPABILITY_5GNR);
+
     /* For now, we don't care about the capability combinations, just merge all
      * combinations in a single mask */
     if (mm_modem_get_supported_capabilities(self->_priv.modem_iface, &supported, &n_supported)) {
diff --git a/src/libnm-core-public/nm-dbus-interface.h b/src/libnm-core-public/nm-dbus-interface.h
index d67637327..fe2a6c09d 100644
--- a/src/libnm-core-public/nm-dbus-interface.h
+++ b/src/libnm-core-public/nm-dbus-interface.h
@@ -443,6 +443,8 @@ typedef enum { /*< flags >*/
                NM_DEVICE_MODEM_CAPABILITY_LTE       = 0x00000008,
                NM_DEVICE_MODEM_CAPABILITY_5GNR      = 0x00000040,
 } NMDeviceModemCapabilities;
+/* Note: the numeric values of NMDeviceModemCapabilities must be identical to the values
+ * in MMModemCapability. See the G_STATIC_ASSERT() in nm-modem-broadband.c's get_capabilities().  */
 
 /**
  * NMWimaxNspNetworkType: