diff --git a/src/arch/i386/drivers/net/undiload.c b/src/arch/i386/drivers/net/undiload.c
index 0edfa35d..f0f15e6a 100644
--- a/src/arch/i386/drivers/net/undiload.c
+++ b/src/arch/i386/drivers/net/undiload.c
@@ -38,6 +38,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  */
 
+/* Disambiguate the various error causes */
+#define EINFO_EUNDILOAD							\
+	__einfo_uniqify ( EINFO_EPLATFORM, 0x01,			\
+			  "UNDI loader error" )
+#define EUNDILOAD( status ) EPLATFORM ( EINFO_EUNDILOAD, status )
+
 /** Parameter block for calling UNDI loader */
 static struct s_UNDI_LOADER __bss16 ( undi_loader );
 #define undi_loader __use_data16 ( undi_loader )
@@ -109,9 +115,7 @@ int undi_load ( struct undi_device *undi, struct undi_rom *undirom ) {
 		/* Clear entry point */
 		memset ( &undi_loader_entry, 0, sizeof ( undi_loader_entry ) );
 
-		rc = -undi_loader.Status;
-		if ( rc == 0 ) /* Paranoia */
-			rc = -EIO;
+		rc = -EUNDILOAD ( undi_loader.Status );
 		DBGC ( undi, "UNDI %p loader failed: %s\n",
 		       undi, strerror ( rc ) );
 		return rc;
diff --git a/src/arch/i386/interface/pxe/pxe_call.c b/src/arch/i386/interface/pxe/pxe_call.c
index b8e73a06..7fce75a9 100644
--- a/src/arch/i386/interface/pxe/pxe_call.c
+++ b/src/arch/i386/interface/pxe/pxe_call.c
@@ -32,6 +32,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
  * PXE API entry point
  */
 
+/* Disambiguate the various error causes */
+#define EINFO_EPXENBP							\
+	__einfo_uniqify ( EINFO_EPLATFORM, 0x01,			\
+			  "External PXE NBP error" )
+#define EPXENBP( status ) EPLATFORM ( EINFO_EPXENBP, status )
+
 /** Vector for chaining INT 1A */
 extern struct segoff __text16 ( pxe_int_1a_vector );
 #define pxe_int_1a_vector __use_text16 ( pxe_int_1a_vector )
@@ -257,7 +263,7 @@ rmjmp_buf pxe_restart_nbp;
 int pxe_start_nbp ( void ) {
 	int jmp;
 	int discard_b, discard_c, discard_d, discard_D;
-	uint16_t rc;
+	uint16_t status;
 
 	/* Allow restarting NBP via PXENV_RESTART_TFTP */
 	jmp = rmsetjmp ( pxe_restart_nbp );
@@ -271,7 +277,7 @@ int pxe_start_nbp ( void ) {
 					   "sti\n\t"
 					   "lcall $0, $0x7c00\n\t"
 					   "addw $4, %%sp\n\t" )
-			       : "=a" ( rc ), "=b" ( discard_b ),
+			       : "=a" ( status ), "=b" ( discard_b ),
 				 "=c" ( discard_c ), "=d" ( discard_d ),
 				 "=D" ( discard_D )
 			       : "a" ( 0 ), "b" ( __from_text16 ( &pxenv ) ),
@@ -279,8 +285,10 @@ int pxe_start_nbp ( void ) {
 			         "d" ( virt_to_phys ( &pxenv ) ),
 				 "D" ( __from_text16 ( &ppxe ) )
 			       : "esi", "ebp", "memory" );
+	if ( status )
+		return -EPXENBP ( status );
 
-	return rc;
+	return 0;
 }
 
 REQUIRE_OBJECT ( pxe_preboot );
diff --git a/src/arch/i386/interface/pxeparent/pxeparent.c b/src/arch/i386/interface/pxeparent/pxeparent.c
index 8b2a2c88..b2c6ffba 100644
--- a/src/arch/i386/interface/pxeparent/pxeparent.c
+++ b/src/arch/i386/interface/pxeparent/pxeparent.c
@@ -31,6 +31,12 @@ FILE_LICENCE ( GPL2_OR_LATER );
  *
  */
 
+/* Disambiguate the various error causes */
+#define EINFO_EPXECALL							\
+	__einfo_uniqify ( EINFO_EPLATFORM, 0x01,			\
+			  "External PXE API error" )
+#define EPXECALL( status ) EPLATFORM ( EINFO_EPXECALL, status )
+
 /**
  * Name PXE API call
  *
@@ -151,16 +157,8 @@ int pxeparent_call ( SEGOFF16_t entry, unsigned int function,
 	/* Determine return status code based on PXENV_EXIT and
 	 * PXENV_STATUS
 	 */
-	if ( exit == PXENV_EXIT_SUCCESS ) {
-		rc = 0;
-	} else {
-		rc = -pxeparent_params.Status;
-		/* Paranoia; don't return success for the combination
-		 * of PXENV_EXIT_FAILURE but PXENV_STATUS_SUCCESS
-		 */
-		if ( rc == 0 )
-			rc = -EIO;
-	}
+	rc = ( ( exit == PXENV_EXIT_SUCCESS ) ?
+	       0 : -EPXECALL ( pxeparent_params.Status ) );
 
 	/* If anything goes wrong, print as much debug information as
 	 * it's possible to give.
diff --git a/src/arch/x86/include/bits/errfile.h b/src/arch/x86/include/bits/errfile.h
index 7b9f3702..5f676c87 100644
--- a/src/arch/x86/include/bits/errfile.h
+++ b/src/arch/x86/include/bits/errfile.h
@@ -33,6 +33,7 @@ FILE_LICENCE ( GPL2_OR_LATER );
 #define ERRFILE_comboot_call   ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000a0000 )
 #define ERRFILE_sdi	       ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000b0000 )
 #define ERRFILE_initrd	       ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000c0000 )
+#define ERRFILE_pxe_call       ( ERRFILE_ARCH | ERRFILE_IMAGE | 0x000d0000 )
 
 #define ERRFILE_undi		 ( ERRFILE_ARCH | ERRFILE_NET | 0x00000000 )
 #define ERRFILE_undiload	 ( ERRFILE_ARCH | ERRFILE_NET | 0x00010000 )