diff --git a/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs b/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
index 634156d0a1..23f617d156 100644
--- a/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
+++ b/BizHawk.Emulation.Common/Database/FirmwareDatabase.cs
@@ -79,6 +79,23 @@ namespace BizHawk.Emulation.Common
 			Option("TI83", "Rom", ti83_108);
 			Option("TI83", "Rom", ti83p_103);
 			Option("TI83", "Rom", ti83p_112);
+
+			// mega cd
+			var eu_mcd1_9210 = File("f891e0ea651e2232af0c5c4cb46a0cae2ee8f356", "eu_mcd1_9210.bin", "Mega CD EU (9210)");
+			var eu_mcd2_9303 = File("7063192ae9f6b696c5b81bc8f0a9fe6f0c400e58", "eu_mcd2_9303.bin", "Mega CD EU (9303)");
+			var eu_mcd2_9306 = File("523b3125fb0ac094e16aa072bc6ccdca22e520e5", "eu_mcd2_9306.bin", "Mega CD EU (9310)");
+			var jp_mcd1_9111 = File("4846f448160059a7da0215a5df12ca160f26dd69", "jp_mcd1_9111.bin", "Mega CD JP (9111)");
+			var jp_mcd1_9112 = File("e4193c6ae44c3cea002707d2a88f1fbcced664de", "jp_mcd1_9112.bin", "Mega CD JP (9112)");
+			var us_scd1_9210 = File("f4f315adcef9b8feb0364c21ab7f0eaf5457f3ed", "us_scd1_9210.bin", "Sega CD US (9210)");
+			var us_scd2_9303 = File("bd3ee0c8ab732468748bf98953603ce772612704", "us_scd2_9303.bin", "Sega CD US (9303)");
+
+			Option("GEN", "CD_BIOS_EU", eu_mcd1_9210);
+			Option("GEN", "CD_BIOS_EU", eu_mcd2_9303);
+			Option("GEN", "CD_BIOS_EU", eu_mcd2_9306);
+			Option("GEN", "CD_BIOS_JP", jp_mcd1_9111);
+			Option("GEN", "CD_BIOS_JP", jp_mcd1_9112);
+			Option("GEN", "CD_BIOS_US", us_scd1_9210);
+			Option("GEN", "CD_BIOS_US", us_scd2_9303);	
 		}
 
 		//adds a defined firmware ID to the database
diff --git a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
index 77d9e4b92e..8848cac8f2 100644
--- a/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
+++ b/BizHawk.Emulation.Cores/Consoles/Sega/gpgx/GPGX.cs
@@ -147,6 +147,11 @@ namespace BizHawk.Emulation.Cores.Consoles.Sega.gpgx
 					return 0;
 				}
 				srcdata = GetCDData();
+				if (srcdata.Length != maxsize)
+				{
+					Console.WriteLine("Couldn't satisfy firmware request PRIMARY_CD because of struct size.");
+					return 0;
+				}
 			}
 			else
 			{