diff --git a/library/psa_crypto.c b/library/psa_crypto.c
index dfbb680..01dbf3c 100644
--- a/library/psa_crypto.c
+++ b/library/psa_crypto.c
@@ -148,6 +148,10 @@
 
 static psa_global_data_t global_data;
 
+#define GUARD_MODULE_INITIALIZED        \
+    if( global_data.initialized == 0 )  \
+        return( PSA_ERROR_BAD_STATE );
+
 static psa_status_t mbedtls_to_psa_error( int ret )
 {
     /* If there's both a high-level code and low-level code, dispatch on
@@ -3360,8 +3364,10 @@
 psa_status_t psa_generate_random( uint8_t *output,
                                   size_t output_size )
 {
-    int ret = mbedtls_ctr_drbg_random( &global_data.ctr_drbg,
-                                       output, output_size );
+    int ret;
+    GUARD_MODULE_INITIALIZED;
+
+    ret = mbedtls_ctr_drbg_random( &global_data.ctr_drbg, output, output_size );
     return( mbedtls_to_psa_error( ret ) );
 }