diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index 490085c..2b652bb 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -7003,7 +7003,6 @@ int iso_image_hfsplus_bless(IsoImage *img, enum IsoHfsplusBlessings blessing,
                                                     (FAILURE, HIGH, -343) */
 #define ISO_AAIP_NON_USER_NAME    0xE830FEA9
 
-
 /** Too many references on a single IsoExternalFilterCommand
                                                     (FAILURE, HIGH, -344) */
 #define ISO_EXTF_TOO_OFTEN        0xE830FEA8
@@ -7171,9 +7170,12 @@ int iso_image_hfsplus_bless(IsoImage *img, enum IsoHfsplusBlessings blessing,
                                                      (FAILURE, HIGH, -382) */
 #define ISO_SECT_SCATTERED          0xE830FE82
 
-/** Too many Apple Partition Map entries requested (FAILURE, HIGH, -383)*/
+/** Too many Apple Partition Map entries requested (FAILURE, HIGH, -383) */
 #define ISO_BOOT_TOO_MANY_APM       0xE830FE81
 
+/** Overlapping Apple Partition Map entries requested (FAILURE, HIGH, -384) */
+#define ISO_BOOT_APM_OVERLAP        0xE830FE80
+
 
 
 /* Internal developer note: 
diff --git a/libisofs/messages.c b/libisofs/messages.c
index d2587eb..1ea9f2a 100644
--- a/libisofs/messages.c
+++ b/libisofs/messages.c
@@ -476,6 +476,8 @@ const char *iso_error_to_msg(int errcode)
         return "File sections do not form consecutive array of blocks";
     case ISO_BOOT_TOO_MANY_APM:
         return "Too many Apple Partition Map entries requested";
+    case ISO_BOOT_APM_OVERLAP:
+        return "Overlapping Apple Partition Map entries requested";
     default:
         return "Unknown error";
     }
diff --git a/libisofs/system_area.c b/libisofs/system_area.c
index cbb0e4a..b4d71c7 100644
--- a/libisofs/system_area.c
+++ b/libisofs/system_area.c
@@ -800,8 +800,10 @@ static int iso_write_apm(Ecma119Image *t, uint32_t img_blocks, uint8_t *buf)
     if (t->apm_req_count <= 0) {
         /*
         ret = iso_quick_apm_entry(t, 16, 20, "Test1_name_16_20", "Test1_type");
-        */
         ret = iso_quick_apm_entry(t, 30, 20, "Test1_name_30_20", "Test1_type");
+        */
+        /* >>> Caution: Size 90 causes intentional partition overlap error */
+        ret = iso_quick_apm_entry(t, 30, 90, "BAD_30_90_BAD", "Test1_type");
         if (ret < 0)
             return ret;
         ret = iso_quick_apm_entry(t, 100, 400, "Test2_name_100_400",
@@ -846,16 +848,15 @@ static int iso_write_apm(Ecma119Image *t, uint32_t img_blocks, uint8_t *buf)
                        t->apm_req[i - 1]->block_count;
         }
         if (part_end > goal) {
-
-            /* >>> Overlapping partition. */;
-            /* >>> Vladimir: "Throw error." */;
-
+            iso_msg_submit(t->image->id, ISO_BOOT_APM_OVERLAP, 0,
+               "Program error: APM partitions %d and %d oberlap by %lu blocks",
+               i - 1, i, part_end - goal);
+            return ISO_BOOT_APM_OVERLAP;
         } 
         if (part_end < goal) {
             sprintf(gap_name, "Gap%d", gap_counter);
             gap_counter++;
-            ret = iso_quick_apm_entry(t, part_end,
-                                      goal - part_end,
+            ret = iso_quick_apm_entry(t, part_end, goal - part_end,
                                       gap_name, "ISO9660_data");
             if (ret < 0)
                 return ret;