diff --git a/pkg/provision/storage/perWorkspaceStorage.go b/pkg/provision/storage/perWorkspaceStorage.go
index 5fcd276f4..7cf66c74b 100644
--- a/pkg/provision/storage/perWorkspaceStorage.go
+++ b/pkg/provision/storage/perWorkspaceStorage.go
@@ -166,6 +166,16 @@ func (p *PerWorkspaceStorageProvisioner) rewriteContainerVolumeMounts(workspaceI
 	return nil
 }
 
+// Calculates the per-workspace PVC size required for the given devworkspace based on the following rules:
+//
+// 1. If all volumes in the devworkspace specify their size, the computed PVC size will be used.
+//
+// 2. If all volumes in the devworkspace either specify their size or are ephemeral, the computed PVC size will be used.
+//
+//  3. If at least one volume in the devworkspace specifies its size, and the computed PVC size is greater
+//     than the default per-workspace PVC size, the computed PVC size will be used.
+//
+// 4. Container components with mountSources enabled in the devworkspace are treated as if they were volumes with an unspecified size.
 func getPVCSize(workspace *common.DevWorkspaceWithConfig, namespacedConfig *nsconfig.NamespacedConfig) (*resource.Quantity, error) {
 	defaultPVCSize := *workspace.Config.Workspace.DefaultStorageSize.PerWorkspace
 
@@ -189,6 +199,15 @@ func getPVCSize(workspace *common.DevWorkspaceWithConfig, namespacedConfig *nsco
 			}
 			requiredPVCSize.Add(volumeSize)
 		}
+		if component.Container != nil {
+			if component.Container.MountSources != nil && *component.Container.MountSources {
+				// Edge case: If the project source code is being mounted to a container component
+				// then an undefined amount of persistent storage is required.
+				// We treat this case as if there was a volume component with no size defined.
+				allVolumeSizesDefined = false
+				continue
+			}
+		}
 	}
 
 	// Use the calculated PVC size if it's greater than default PVC size
diff --git a/pkg/provision/storage/testdata/perWorkspace-storage/use-default-size-when-mount-sources-used.yaml b/pkg/provision/storage/testdata/perWorkspace-storage/use-default-size-when-mount-sources-used.yaml
new file mode 100644
index 000000000..5d1b1cc71
--- /dev/null
+++ b/pkg/provision/storage/testdata/perWorkspace-storage/use-default-size-when-mount-sources-used.yaml
@@ -0,0 +1,39 @@
+name: "Uses default PVC size when no volumes define their size but mountSources used"
+
+input:
+  devworkspaceId: "test-workspaceid"
+  podAdditions:
+    containers:
+      - name: testing-container-1
+        image: testing-image
+        volumeMounts:
+          - name: "projects"
+            mountPath: "/projects-mountpath"
+    initContainers:
+      - name: testing-initContainer-1
+        image: testing-image
+
+  workspace:
+    components:
+      - name: testing-container-1
+        container:
+          image: testing-image-1
+          mountSources: true
+
+output:
+  podAdditions:
+    containers:
+      - name: testing-container-1
+        image: testing-image
+        volumeMounts:
+          - name: storage-test-workspaceid
+            subPath: "projects"
+            mountPath: "/projects-mountpath"
+    initContainers:
+      - name: testing-initContainer-1
+        image: testing-image
+
+    volumes:
+      - name: storage-test-workspaceid
+        persistentVolumeClaim:
+          claimName: storage-test-workspaceid