diff --git a/toolbox/mm.cpp b/toolbox/mm.cpp
index aad4d28..3dbaec9 100644
--- a/toolbox/mm.cpp
+++ b/toolbox/mm.cpp
@@ -271,6 +271,7 @@ namespace MM
 		 Log("%04x CompactMem(%08x)\n", trap, cbNeeded);
 
 
+		 SetMemError(0);
 		 return mplite_maxmem(&pool);
 	}
 
@@ -288,6 +289,7 @@ namespace MM
 
 		Log("%04x MaxMem()\n", trap);
 
+		SetMemError(0);
 		return mplite_maxmem(&pool);
 	}
 
@@ -305,9 +307,33 @@ namespace MM
 
 		Log("%04x FreeMem()\n", trap);
 
+		SetMemError(0);
 		return mplite_freemem(&pool);
 	}
 
+	uint16_t ReserveMem(uint16_t trap)
+	{
+		/* 
+		 * on entry:
+		 * D0: cbNeeded (long word)
+		 *
+		 * on exit:
+		 * D0: Result code.
+		 *
+		 */
+
+		uint32_t cbNeeded = cpuGetDReg(0);
+		uint32_t available;
+
+		Log("%04x ReserveMem($%08x)\n", trap, cbNeeded);
+
+		available = mplite_maxmem(&pool);
+		// TODO -- if available < cbNeeded, purge handle and retry?
+		if (available < cbNeeded) return SetMemError(memFullErr);
+
+		return SetMemError(0);
+	}
+
 
 	uint16_t MoveHHi(uint16_t trap)
 	{
diff --git a/toolbox/mm.h b/toolbox/mm.h
index d3e3839..478c354 100644
--- a/toolbox/mm.h
+++ b/toolbox/mm.h
@@ -28,7 +28,9 @@ namespace MM
 	uint32_t CompactMem(uint16_t trap);
 	uint32_t MaxMem(uint16_t trap);
 	uint32_t FreeMem(uint16_t trap);
+	uint16_t ReserveMem(uint16_t trap);
 	
+
 	uint16_t DisposeHandle(uint16_t trap);
 	uint16_t DisposePtr(uint16_t trap);
 
diff --git a/toolbox/toolbox.cpp b/toolbox/toolbox.cpp
index 011431f..b1f8033 100644
--- a/toolbox/toolbox.cpp
+++ b/toolbox/toolbox.cpp
@@ -141,6 +141,10 @@ namespace ToolBox {
 				d0 = MM::CompactMem(trap);
 				break;
 
+			case 0xa040:
+				d0 = MM::ReserveMem(trap);
+				break;
+
 			case 0xa055:
 				d0 = MM::StripAddress(trap);
 				break;