diff --git a/nuttx/ChangeLog b/nuttx/ChangeLog
index 80d889b3b5..adb52afce7 100644
--- a/nuttx/ChangeLog
+++ b/nuttx/ChangeLog
@@ -3417,4 +3417,6 @@
 	  not an ILI93xx.
 	* configs/shenzhou/src/up_ssd1289.c: The LCD is basically functional
 	  on the Shenzhou board.
+	* graphics/nxmu:  Correct some bad parameter checking that caused
+	  failures when DEBUG was enabled.
 
diff --git a/nuttx/Kconfig b/nuttx/Kconfig
index f4f6abe7e0..0fe6eb0f7c 100644
--- a/nuttx/Kconfig
+++ b/nuttx/Kconfig
@@ -230,7 +230,11 @@ config DEBUG_VERBOSE
 	bool "Enable Debug Verbose Output"
 	default n
 	---help---
-		Enables verbose debug output (assuming debug output is enabled)
+		Enables verbose debug output (assuming debug output is enabled).  As a
+		general rule, when DEBUG is enabled only errors will be reported in the debug
+		output.  But if you also enable DEBUG_VERBOSE, then very chatty (and
+		often annoying) output will be generated.  This means there are two levels
+		of debug output:  errors-only and everything.
 
 config DEBUG_ENABLE
 	bool "Enable Debug Controls"
diff --git a/nuttx/drivers/input/ads7843e.c b/nuttx/drivers/input/ads7843e.c
index 555ce34806..07e5e515df 100644
--- a/nuttx/drivers/input/ads7843e.c
+++ b/nuttx/drivers/input/ads7843e.c
@@ -572,7 +572,7 @@ static void ads7843e_worker(FAR void *arg)
   /* Check for pen up or down by reading the PENIRQ GPIO. */
 
   pendown = config->pendown(config);
-dbg("pendown: %d\n", pendown); // REMOVE ME
+
   /* Handle the change from pen down to pen up */
 
   if (!pendown)
@@ -643,7 +643,6 @@ dbg("pendown: %d\n", pendown); // REMOVE ME
   /* Exit, re-enabling ADS7843E interrupts */
 
 errout:
-dbg("Exiting\n"); // REMOVE ME
   (void)ads7843e_sendcmd(priv, ADS7843_CMD_ENABPINIRQ);
   config->enable(config, true);
 }
diff --git a/nuttx/graphics/nxmu/nx_block.c b/nuttx/graphics/nxmu/nx_block.c
index 2f069f0962..3a051f9d7d 100644
--- a/nuttx/graphics/nxmu/nx_block.c
+++ b/nuttx/graphics/nxmu/nx_block.c
@@ -111,8 +111,8 @@ int nx_block(NXWINDOW hwnd, FAR void *arg)
 #ifdef CONFIG_DEBUG
   if (!hwnd)
     {
-      errno = EINVAL;
-      return NULL;
+      set_errno(EINVAL);
+      return ERROR;
     }
 #endif
 
diff --git a/nuttx/graphics/nxmu/nxmu_sendclient.c b/nuttx/graphics/nxmu/nxmu_sendclient.c
index 8b7f121042..a59fa23634 100644
--- a/nuttx/graphics/nxmu/nxmu_sendclient.c
+++ b/nuttx/graphics/nxmu/nxmu_sendclient.c
@@ -93,9 +93,9 @@ int nxmu_sendclient(FAR struct nxfe_conn_s *conn, FAR const void *msg,
   /* Sanity checking */
 
 #ifdef CONFIG_DEBUG
-  if (!conn || conn->swrmq)
+  if (!conn || !conn->swrmq)
     {
-      errno = EINVAL;
+      set_errno(EINVAL);
       return ERROR;
     }
 #endif
diff --git a/nuttx/graphics/nxmu/nxmu_sendserver.c b/nuttx/graphics/nxmu/nxmu_sendserver.c
index 7007b81da9..03ece4e7f7 100644
--- a/nuttx/graphics/nxmu/nxmu_sendserver.c
+++ b/nuttx/graphics/nxmu/nxmu_sendserver.c
@@ -93,9 +93,9 @@ int nxmu_sendserver(FAR struct nxfe_conn_s *conn, FAR const void *msg,
   /* Sanity checking */
 
 #ifdef CONFIG_DEBUG
-  if (!conn || conn->cwrmq)
+  if (!conn || !conn->cwrmq)
     {
-      errno = EINVAL;
+      set_errno(EINVAL);
       return ERROR;
     }
 #endif