diff --git a/ofproto/ofproto-dpif-upcall.c b/ofproto/ofproto-dpif-upcall.c
index ccf97266c0b9..d22f7f07361f 100644
--- a/ofproto/ofproto-dpif-upcall.c
+++ b/ofproto/ofproto-dpif-upcall.c
@@ -129,10 +129,10 @@ struct udpif {
     struct dpif_backer *backer;        /* Opaque dpif_backer pointer. */
 
     struct handler *handlers;          /* Upcall handlers. */
-    size_t n_handlers;
+    uint32_t n_handlers;
 
     struct revalidator *revalidators;  /* Flow revalidators. */
-    size_t n_revalidators;
+    uint32_t n_revalidators;
 
     struct latch exit_latch;           /* Tells child threads to exit. */
 
@@ -335,8 +335,8 @@ static int process_upcall(struct udpif *, struct upcall *,
                           struct ofpbuf *odp_actions, struct flow_wildcards *);
 static void handle_upcalls(struct udpif *, struct upcall *, size_t n_upcalls);
 static void udpif_stop_threads(struct udpif *, bool delete_flows);
-static void udpif_start_threads(struct udpif *, size_t n_handlers,
-                                size_t n_revalidators);
+static void udpif_start_threads(struct udpif *, uint32_t n_handlers,
+                                uint32_t n_revalidators);
 static void udpif_pause_revalidators(struct udpif *);
 static void udpif_resume_revalidators(struct udpif *);
 static void *udpif_upcall_handler(void *);
@@ -562,8 +562,8 @@ udpif_stop_threads(struct udpif *udpif, bool delete_flows)
 
 /* Starts the handler and revalidator threads. */
 static void
-udpif_start_threads(struct udpif *udpif, size_t n_handlers_,
-                    size_t n_revalidators_)
+udpif_start_threads(struct udpif *udpif, uint32_t n_handlers_,
+                    uint32_t n_revalidators_)
 {
     if (udpif && n_handlers_ && n_revalidators_) {
         /* Creating a thread can take a significant amount of time on some
@@ -632,8 +632,8 @@ udpif_resume_revalidators(struct udpif *udpif)
  * datapath handle must have packet reception enabled before starting
  * threads. */
 void
-udpif_set_threads(struct udpif *udpif, size_t n_handlers_,
-                  size_t n_revalidators_)
+udpif_set_threads(struct udpif *udpif, uint32_t n_handlers_,
+                  uint32_t n_revalidators_)
 {
     ovs_assert(udpif);
     ovs_assert(n_handlers_ && n_revalidators_);
@@ -691,8 +691,8 @@ udpif_get_memory_usage(struct udpif *udpif, struct simap *usage)
 void
 udpif_flush(struct udpif *udpif)
 {
-    size_t n_handlers_ = udpif->n_handlers;
-    size_t n_revalidators_ = udpif->n_revalidators;
+    uint32_t n_handlers_ = udpif->n_handlers;
+    uint32_t n_revalidators_ = udpif->n_revalidators;
 
     udpif_stop_threads(udpif, true);
     dpif_flow_flush(udpif->dpif);
diff --git a/ofproto/ofproto-dpif-upcall.h b/ofproto/ofproto-dpif-upcall.h
index 693107ae56c1..b4dfed32046e 100644
--- a/ofproto/ofproto-dpif-upcall.h
+++ b/ofproto/ofproto-dpif-upcall.h
@@ -16,6 +16,7 @@
 #define OFPROTO_DPIF_UPCALL_H
 
 #include <stddef.h>
+#include <inttypes.h>
 
 struct dpif;
 struct dpif_backer;
@@ -31,8 +32,8 @@ struct simap;
 void udpif_init(void);
 struct udpif *udpif_create(struct dpif_backer *, struct dpif *);
 void udpif_run(struct udpif *udpif);
-void udpif_set_threads(struct udpif *, size_t n_handlers,
-                       size_t n_revalidators);
+void udpif_set_threads(struct udpif *, uint32_t n_handlers,
+                       uint32_t n_revalidators);
 void udpif_destroy(struct udpif *);
 void udpif_revalidate(struct udpif *);
 void udpif_get_memory_usage(struct udpif *, struct simap *usage);
diff --git a/ofproto/ofproto-provider.h b/ofproto/ofproto-provider.h
index 9ad2b71d23eb..57c7d17cb28f 100644
--- a/ofproto/ofproto-provider.h
+++ b/ofproto/ofproto-provider.h
@@ -534,7 +534,7 @@ extern unsigned ofproto_min_revalidate_pps;
 
 /* Number of upcall handler and revalidator threads. Only affects the
  * ofproto-dpif implementation. */
-extern size_t n_handlers, n_revalidators;
+extern uint32_t n_handlers, n_revalidators;
 
 static inline struct rule *rule_from_cls_rule(const struct cls_rule *);
 
diff --git a/ofproto/ofproto.c b/ofproto/ofproto.c
index 80ec2d9ac9c7..53002f082b52 100644
--- a/ofproto/ofproto.c
+++ b/ofproto/ofproto.c
@@ -309,7 +309,7 @@ unsigned ofproto_max_idle = OFPROTO_MAX_IDLE_DEFAULT;
 unsigned ofproto_max_revalidator = OFPROTO_MAX_REVALIDATOR_DEFAULT;
 unsigned ofproto_min_revalidate_pps = OFPROTO_MIN_REVALIDATE_PPS_DEFAULT;
 
-size_t n_handlers, n_revalidators;
+uint32_t n_handlers, n_revalidators;
 
 /* Map from datapath name to struct ofproto, for use by unixctl commands. */
 static struct hmap all_ofprotos = HMAP_INITIALIZER(&all_ofprotos);
