diff --git a/library/entropy.c b/library/entropy.c
index 3622ad2..b45384d 100644
--- a/library/entropy.c
+++ b/library/entropy.c
@@ -60,6 +60,9 @@
 {
     memset( ctx, 0, sizeof(mbedtls_entropy_context) );
 
+     /* Reminder: Update ENTROPY_HAVE_STRONG in the test files
+      * when adding more strong entropy sources here. */
+
 #if defined(MBEDTLS_THREADING_C)
     mbedtls_mutex_init( &ctx->mutex );
 #endif
diff --git a/tests/suites/helpers.function b/tests/suites/helpers.function
index 6af918c..b80831e 100644
--- a/tests/suites/helpers.function
+++ b/tests/suites/helpers.function
@@ -55,6 +55,18 @@
 }
 #endif
 
+/* Helper flags for complex dependencies */
+
+/* Indicates whether we expect mbedtls_entropy_init
+ * to initialize some strong entropy source. */
+#if defined(MBEDTLS_TEST_NULL_ENTROPY) ||             \
+    ( !defined(MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES) && \
+      ( !defined(MBEDTLS_NO_PLATFORM_ENTROPY)  ||     \
+         defined(MBEDTLS_HAVEGE_C)             ||     \
+         defined(MBEDTLS_ENTROPY_HARDWARE_ALT) ) )
+#define ENTROPY_HAVE_STRONG
+#endif
+
 static int unhexify( unsigned char *obuf, const char *ibuf )
 {
     unsigned char c, c2;