diff --git a/src/testzzuf/test_get.c b/src/testzzuf/test_get.c
index 9ef0d4f7..0ab4fcf9 100644
--- a/src/testzzuf/test_get.c
+++ b/src/testzzuf/test_get.c
@@ -75,6 +75,16 @@ ahc_echo (void *cls,
   enum MHD_Result ret;
   (void) version; (void) upload_data; (void) upload_data_size;       /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp (me, method))
     return MHD_NO;              /* unexpected method */
   if (&ptr != *unused)
diff --git a/src/testzzuf/test_get_chunked.c b/src/testzzuf/test_get_chunked.c
index ed974828..9fdab22a 100644
--- a/src/testzzuf/test_get_chunked.c
+++ b/src/testzzuf/test_get_chunked.c
@@ -108,6 +108,16 @@ ahc_echo (void *cls,
   (void) upload_data;
   (void) upload_data_size;     /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp (me, method))
     return MHD_NO;              /* unexpected method */
   if (&aptr != *ptr)
diff --git a/src/testzzuf/test_long_header.c b/src/testzzuf/test_long_header.c
index f62fe07b..ac53bad6 100644
--- a/src/testzzuf/test_long_header.c
+++ b/src/testzzuf/test_long_header.c
@@ -85,6 +85,16 @@ ahc_echo (void *cls,
   (void) version; (void) upload_data;      /* Unused. Silent compiler warning. */
   (void) upload_data_size; (void) unused;  /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp (me, method))
     return MHD_NO;              /* unexpected method */
   response = MHD_create_response_from_buffer (strlen (url),
diff --git a/src/testzzuf/test_post.c b/src/testzzuf/test_post.c
index e3d8512c..8377af06 100644
--- a/src/testzzuf/test_post.c
+++ b/src/testzzuf/test_post.c
@@ -122,6 +122,16 @@ ahc_echo (void *cls,
   enum MHD_Result ret;
   (void) cls; (void) version;      /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp ("POST", method))
   {
     return MHD_NO;              /* unexpected method */
diff --git a/src/testzzuf/test_post_form.c b/src/testzzuf/test_post_form.c
index f994ab24..85a5d3d7 100644
--- a/src/testzzuf/test_post_form.c
+++ b/src/testzzuf/test_post_form.c
@@ -125,6 +125,16 @@ ahc_echo (void *cls,
   enum MHD_Result ret;
   (void) cls; (void) version;      /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp ("POST", method))
   {
     return MHD_NO;              /* unexpected method */
diff --git a/src/testzzuf/test_put.c b/src/testzzuf/test_put.c
index 4658d0d4..86f7b63a 100644
--- a/src/testzzuf/test_put.c
+++ b/src/testzzuf/test_put.c
@@ -90,6 +90,16 @@ ahc_echo (void *cls,
   enum MHD_Result ret;
   (void) version; (void) unused;   /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp ("PUT", method))
     return MHD_NO;              /* unexpected method */
   if ((*done) == 0)
diff --git a/src/testzzuf/test_put_chunked.c b/src/testzzuf/test_put_chunked.c
index 35196843..c762c27b 100644
--- a/src/testzzuf/test_put_chunked.c
+++ b/src/testzzuf/test_put_chunked.c
@@ -91,6 +91,16 @@ ahc_echo (void *cls,
   int have;
   (void) version; (void) unused;   /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp ("PUT", method))
     return MHD_NO;              /* unexpected method */
   if ((*done) < 8)
diff --git a/src/testzzuf/test_put_large.c b/src/testzzuf/test_put_large.c
index abda22cb..3a3d7fb0 100644
--- a/src/testzzuf/test_put_large.c
+++ b/src/testzzuf/test_put_large.c
@@ -98,6 +98,16 @@ ahc_echo (void *cls,
   enum MHD_Result ret;
   (void) version; (void) unused; /* Unused. Silent compiler warning. */
 
+  if (NULL == url)
+    fprintf (stderr, "The \"url\" parameter is NULL.\n");
+  if (NULL == method)
+    fprintf (stderr, "The \"method\" parameter is NULL.\n");
+  if (NULL == version)
+    fprintf (stderr, "The \"version\" parameter is NULL.\n");
+  if (NULL == upload_data_size)
+    fprintf (stderr, "The \"upload_data_size\" parameter is NULL.\n");
+  if ((0 != *upload_data_size) && (NULL == upload_data))
+    fprintf (stderr, "Upload data is NULL with non-zero size.\n");
   if (0 != strcmp ("PUT", method))
     return MHD_NO;              /* unexpected method */
   if ((*done) == 0)