diff --git a/include/jemalloc/internal/hpa.h b/include/jemalloc/internal/hpa.h
index a384d04a..117c1c20 100644
--- a/include/jemalloc/internal/hpa.h
+++ b/include/jemalloc/internal/hpa.h
@@ -153,7 +153,7 @@ struct hpa_shard_s {
 	peak_demand_t peak_demand;
 };
 
-bool hpa_hugepage_size_exceeds_limit();
+bool hpa_hugepage_size_exceeds_limit(void);
 /*
  * Whether or not the HPA can be used given the current configuration.  This is
  * is not necessarily a guarantee that it backs its allocations by hugepages,
diff --git a/include/jemalloc/internal/sz.h b/include/jemalloc/internal/sz.h
index e6cfa6a9..3a32e232 100644
--- a/include/jemalloc/internal/sz.h
+++ b/include/jemalloc/internal/sz.h
@@ -55,7 +55,7 @@ extern size_t sz_large_pad;
 extern void sz_boot(const sc_data_t *sc_data, bool cache_oblivious);
 
 JEMALLOC_ALWAYS_INLINE bool
-sz_large_size_classes_disabled() {
+sz_large_size_classes_disabled(void) {
 	return opt_disable_large_size_classes;
 }
 
diff --git a/src/eset.c b/src/eset.c
index 677162ff..b4666e2c 100644
--- a/src/eset.c
+++ b/src/eset.c
@@ -155,7 +155,7 @@ eset_remove(eset_t *eset, edata_t *edata) {
 	    cur_extents_npages - (size >> LG_PAGE), ATOMIC_RELAXED);
 }
 
-edata_t *
+static edata_t *
 eset_enumerate_alignment_search(eset_t *eset, size_t size, pszind_t bin_ind,
     size_t alignment) {
 	if (edata_heap_empty(&eset->bins[bin_ind].heap)) {
@@ -191,7 +191,7 @@ eset_enumerate_alignment_search(eset_t *eset, size_t size, pszind_t bin_ind,
 	return NULL;
 }
 
-edata_t *
+static edata_t *
 eset_enumerate_search(eset_t *eset, size_t size, pszind_t bin_ind,
     bool exact_only, edata_cmp_summary_t *ret_summ) {
 	if (edata_heap_empty(&eset->bins[bin_ind].heap)) {
diff --git a/src/hpa.c b/src/hpa.c
index 50614e42..9b7ff744 100644
--- a/src/hpa.c
+++ b/src/hpa.c
@@ -26,7 +26,7 @@ static void hpa_dalloc_batch(tsdn_t *tsdn, pai_t *self,
 static uint64_t hpa_time_until_deferred_work(tsdn_t *tsdn, pai_t *self);
 
 bool
-hpa_hugepage_size_exceeds_limit() {
+hpa_hugepage_size_exceeds_limit(void) {
 	return HUGEPAGE > HUGEPAGE_MAX_EXPECTED_SIZE;
 }
 
diff --git a/src/pac.c b/src/pac.c
index e9ba7957..0e435717 100644
--- a/src/pac.c
+++ b/src/pac.c
@@ -112,7 +112,7 @@ pac_may_have_muzzy(pac_t *pac) {
 	return pac_decay_ms_get(pac, extent_state_muzzy) != 0;
 }
 
-size_t pac_alloc_retained_batched_size(size_t size) {
+static size_t pac_alloc_retained_batched_size(size_t size) {
 	if (size > SC_LARGE_MAXCLASS) {
 		/*
 		 * A valid input with usize SC_LARGE_MAXCLASS could still
diff --git a/src/prof_sys.c b/src/prof_sys.c
index 642d8c89..e3b7bbcb 100644
--- a/src/prof_sys.c
+++ b/src/prof_sys.c
@@ -586,7 +586,7 @@ prof_getpid(void) {
 }
 
 static long
-prof_get_pid_namespace() {
+prof_get_pid_namespace(void) {
 	long ret = 0;
 
 #if defined(_WIN32) || defined(__APPLE__)
diff --git a/src/psset.c b/src/psset.c
index 97694301..afe9f1c1 100644
--- a/src/psset.c
+++ b/src/psset.c
@@ -337,7 +337,7 @@ psset_update_end(psset_t *psset, hpdata_t *ps) {
 	hpdata_assert_consistent(ps);
 }
 
-hpdata_t *
+static hpdata_t *
 psset_enumerate_search(psset_t *psset, pszind_t pind, size_t size) {
 	if (hpdata_age_heap_empty(&psset->pageslabs[pind])) {
 		return NULL;