diff --git a/src/internal/scratch3reader.cpp b/src/internal/scratch3reader.cpp
index c747a023..af41223c 100644
--- a/src/internal/scratch3reader.cpp
+++ b/src/internal/scratch3reader.cpp
@@ -404,12 +404,16 @@ bool Scratch3Reader::load()
             }
 
             // width
-            READER_STEP(step, "monitor -> width");
-            monitor->setWidth(jsonMonitor["width"]);
+            if (jsonMonitor.contains("width")) {
+                READER_STEP(step, "monitor -> width");
+                monitor->setWidth(jsonMonitor["width"]);
+            }
 
             // height
-            READER_STEP(step, "monitor -> height");
-            monitor->setHeight(jsonMonitor["height"]);
+            if (jsonMonitor.contains("height")) {
+                READER_STEP(step, "monitor -> height");
+                monitor->setHeight(jsonMonitor["height"]);
+            }
 
             // x
             READER_STEP(step, "monitor -> x");
diff --git a/test/load_project/load_project_test.cpp b/test/load_project/load_project_test.cpp
index f95c338a..639e4c0d 100644
--- a/test/load_project/load_project_test.cpp
+++ b/test/load_project/load_project_test.cpp
@@ -701,3 +701,11 @@ TEST(LoadProjectTest, ProjectInvalidTest)
     ASSERT_EQ(p.scratchVersion(), ScratchVersion::Invalid);
     ASSERT_FALSE(p.load());
 }
+
+TEST(LoadProjectTest, LoadNullDimensionMonitor)
+{
+    // Regtest for #448
+    std::string name = "regtest_projects/448_null_monitor_dimension.sb3";
+    Project p(name);
+    ASSERT_TRUE(p.load());
+}
diff --git a/test/regtest_projects/448_null_monitor_dimension.sb3 b/test/regtest_projects/448_null_monitor_dimension.sb3
new file mode 100644
index 00000000..c52a77f2
Binary files /dev/null and b/test/regtest_projects/448_null_monitor_dimension.sb3 differ