diff --git a/base/process.jl b/base/process.jl
index 6aac514191681..cbc251ed6dbca 100644
--- a/base/process.jl
+++ b/base/process.jl
@@ -38,9 +38,13 @@ pipe_writer(p::ProcessChain) = p.in
 # release ownership of the libuv handle
 function uvfinalize(proc::Process)
     if proc.handle != C_NULL
-        disassociate_julia_struct(proc.handle)
-        ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), proc.handle)
-        proc.handle = C_NULL
+        iolock_begin()
+        if proc.handle != C_NULL
+            disassociate_julia_struct(proc.handle)
+            ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), proc.handle)
+            proc.handle = C_NULL
+        end
+        iolock_end()
     end
     nothing
 end
@@ -52,6 +56,7 @@ function uv_return_spawn(p::Ptr{Cvoid}, exit_status::Int64, termsignal::Int32)
     proc = unsafe_pointer_to_objref(data)::Process
     proc.exitcode = exit_status
     proc.termsignal = termsignal
+    disassociate_julia_struct(proc) # ensure that data field is set to C_NULL
     ccall(:jl_close_uv, Cvoid, (Ptr{Cvoid},), proc.handle)
     proc.handle = C_NULL
     lock(proc.exitnotify)
@@ -95,8 +100,9 @@ end
             end
             for io in stdio]
         handle = Libc.malloc(_sizeof_uv_process)
-        disassociate_julia_struct(handle) # ensure that data field is set to C_NULL
+        disassociate_julia_struct(handle)
         (; exec, flags, env, dir) = cmd
+        iolock_begin()
         err = ccall(:jl_spawn, Int32,
                   (Cstring, Ptr{Cstring}, Ptr{Cvoid}, Ptr{Cvoid},
                    Ptr{Tuple{Cint, UInt}}, Int,
@@ -109,13 +115,17 @@ end
             cpumask === nothing ? C_NULL : cpumask,
             cpumask === nothing ? 0 : length(cpumask),
             @cfunction(uv_return_spawn, Cvoid, (Ptr{Cvoid}, Int64, Int32)))
+        if err == 0
+            pp = Process(cmd, handle)
+            associate_julia_struct(handle, pp)
+        else
+            ccall(:jl_forceclose_uv, Cvoid, (Ptr{Cvoid},), handle) # will call free on handle eventually
+        end
+        iolock_end()
     end
     if err != 0
-        ccall(:jl_forceclose_uv, Cvoid, (Ptr{Cvoid},), handle) # will call free on handle eventually
         throw(_UVError("could not spawn " * repr(cmd), err))
     end
-    pp = Process(cmd, handle)
-    associate_julia_struct(handle, pp)
     return pp
 end
 
diff --git a/src/jl_uv.c b/src/jl_uv.c
index d2372b59c4670..d2a78c26bbc72 100644
--- a/src/jl_uv.c
+++ b/src/jl_uv.c
@@ -282,7 +282,7 @@ JL_DLLEXPORT void jl_uv_disassociate_julia_struct(uv_handle_t *handle)
     handle->data = NULL;
 }
 
-#define UV_CLOSED 0x02 // UV_HANDLE_CLOSED on Windows (same value)
+#define UV_HANDLE_CLOSED 0x02
 
 JL_DLLEXPORT int jl_spawn(char *name, char **argv,
                           uv_loop_t *loop, uv_process_t *proc,
@@ -308,7 +308,7 @@ JL_DLLEXPORT int jl_spawn(char *name, char **argv,
         if (!(flags == UV_INHERIT_FD || flags == UV_INHERIT_STREAM || flags == UV_IGNORE)) {
             proc->type = UV_PROCESS;
             proc->loop = loop;
-            proc->flags = UV_CLOSED;
+            proc->flags = UV_HANDLE_CLOSED;
             return UV_EINVAL;
         }
     }