diff --git a/toolbox/mm.cpp b/toolbox/mm.cpp
index 4998880..5fe8e57 100644
--- a/toolbox/mm.cpp
+++ b/toolbox/mm.cpp
@@ -140,7 +140,7 @@ namespace MM
 		 uint32_t cbNeeded = cpuGetDReg(0);
 
 		 fprintf(stderr, "%04x CompactMem(%08x)\n", trap, cbNeeded);
-		 
+
 		 return 0x0f0000;
 	}
 
@@ -257,6 +257,38 @@ namespace MM
 		return SetMemError(0);
 	}
 
+	uint16_t SetPtrSize(uint16_t trap)
+	{
+		/* 
+		 * on entry:
+		 * A0 pointer
+		 * D0 new size
+		 *
+		 * on exit:
+		 * D0 Result code
+		 *
+		 */
+
+		uint32_t mcptr = cpuGetAReg(0);
+		uint32_t newSize = cpuGetDReg(0);
+
+		fprintf(stderr, "%08x SetPtrSize(%08x, %08x)\n", trap, mcptr, newSize);
+
+		auto iter = PtrMap.find(mcptr);
+
+		if (iter == PtrMap.end()) return SetMemError(memWZErr);
+		PtrMap.erase(iter);
+
+		uint8_t *ptr = mcptr + Memory;
+
+		if (mplite_resize(&pool, ptr, newSize) < 0)
+		{
+			return SetMemError(memFullErr);
+		}
+
+		return SetMemError(0);
+	}
+
 	uint16_t NewHandle(uint16_t trap)
 	{
 		/* 
diff --git a/toolbox/mm.h b/toolbox/mm.h
index 88870ff..e0cd7a5 100644
--- a/toolbox/mm.h
+++ b/toolbox/mm.h
@@ -20,6 +20,9 @@ namespace MM
 
 	uint16_t NewPtr(uint16_t trap);
 	uint16_t NewHandle(uint16_t trap);
+
+	uint16_t SetPtrSize(uint16_t);
+	uint16_t SetHandleSize(uint16_t);
 }
 
 
diff --git a/toolbox/toolbox.cpp b/toolbox/toolbox.cpp
index f31b900..6e01741 100644
--- a/toolbox/toolbox.cpp
+++ b/toolbox/toolbox.cpp
@@ -49,6 +49,11 @@ namespace ToolBox {
 				d0 = OS::GetVol(trap);
 				break;
 
+			// SetPtrSize (p: Ptr; newSize: Size);
+			case 0xa020:
+				d0 = MM::SetPtrSize(trap);
+				break;
+
 			case 0xA023:
 				d0 = MM::DisposeHandle(trap);
 				break;