diff --git a/src/vector_of_array.jl b/src/vector_of_array.jl
index af4da6e9..95777e05 100644
--- a/src/vector_of_array.jl
+++ b/src/vector_of_array.jl
@@ -1167,16 +1167,21 @@ end
 # fill!
 # For DiffEqArray it ignores ts and fills only u
 function Base.fill!(VA::AbstractVectorOfArray, x)
-    for i in 1:length(VA.u)
-        if VA[:, i] isa Union{AbstractArray, AbstractVectorOfArray}
-            if ArrayInterface.ismutable(VA.u[i]) || VA.u[i] isa AbstractVectorOfArray
-                fill!(VA[:, i], x)
+    for i in eachindex(VA.u)
+        # Fill the inner array directly instead of through `VA[:, i]`, which
+        # for a ragged inner array builds and returns a zero-padded *copy* —
+        # filling that copy does not touch (and silently drops writes to) the
+        # real storage.
+        ui = VA.u[i]
+        if ui isa Union{AbstractArray, AbstractVectorOfArray}
+            if ArrayInterface.ismutable(ui) || ui isa AbstractVectorOfArray
+                fill!(ui, x)
             else
                 # For immutable arrays like SVector, create a new filled array
-                VA.u[i] = fill(x, StaticArraysCore.similar_type(VA.u[i]))
+                VA.u[i] = fill(x, StaticArraysCore.similar_type(ui))
             end
         else
-            VA[:, i] = x
+            VA.u[i] = x
         end
     end
     return VA
diff --git a/test/Core/interface_tests.jl b/test/Core/interface_tests.jl
index c4aa6ae8..59f45857 100644
--- a/test/Core/interface_tests.jl
+++ b/test/Core/interface_tests.jl
@@ -248,6 +248,14 @@ testda = DiffEqArray(recursivecopy(testva.u), testts)
 fill!(testda, testval)
 @test all(x -> (x == testval), testda)
 
+# fill! on a ragged VectorOfArray must fill every inner array, not just the
+# longest one. `VA[:, i]` zero-pads a shorter inner array into a throwaway
+# copy, so filling through it (instead of through `VA.u[i]` directly) would
+# silently drop the write for every inner array shorter than the max.
+ragged_fill = VectorOfArray([[1.0, 2.0], [3.0], [4.0, 5.0, 6.0]])
+fill!(ragged_fill, 9.0)
+@test ragged_fill.u == [[9.0, 9.0], [9.0], [9.0, 9.0, 9.0]]
+
 # copyto!
 testva = VectorOfArray(collect(0.1:0.1:1.0))
 arr = 0.2:0.2:2.0