diff --git a/src/extent.c b/src/extent.c
index 814f0a32..66cbf05b 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -1256,7 +1256,7 @@ extent_alloc_default(extent_hooks_t *extent_hooks, void *new_addr, size_t size,
 	assert(arena != NULL);
 
 	return extent_alloc_default_impl(tsdn, arena, new_addr, size,
-	    alignment, zero, commit);
+	    ALIGNMENT_CEILING(alignment, PAGE), zero, commit);
 }
 
 static void
@@ -1493,14 +1493,15 @@ extent_alloc_wrapper_hard(tsdn_t *tsdn, arena_t *arena,
 		return NULL;
 	}
 	void *addr;
+	size_t palignment = ALIGNMENT_CEILING(alignment, PAGE);
 	if (*r_extent_hooks == &extent_hooks_default) {
 		/* Call directly to propagate tsdn. */
 		addr = extent_alloc_default_impl(tsdn, arena, new_addr, esize,
-		    alignment, zero, commit);
+		    palignment, zero, commit);
 	} else {
 		extent_hook_pre_reentrancy(tsdn, arena);
 		addr = (*r_extent_hooks)->alloc(*r_extent_hooks, new_addr,
-		    esize, alignment, zero, commit, arena_ind_get(arena));
+		    esize, palignment, zero, commit, arena_ind_get(arena));
 		extent_hook_post_reentrancy(tsdn);
 	}
 	if (addr == NULL) {
diff --git a/src/extent_dss.c b/src/extent_dss.c
index 6c56cf65..69a7bee8 100644
--- a/src/extent_dss.c
+++ b/src/extent_dss.c
@@ -113,7 +113,7 @@ extent_alloc_dss(tsdn_t *tsdn, arena_t *arena, void *new_addr, size_t size,
 
 	cassert(have_dss);
 	assert(size > 0);
-	assert(alignment > 0);
+	assert(alignment == ALIGNMENT_CEILING(alignment, PAGE));
 
 	/*
 	 * sbrk() uses a signed increment argument, so take care not to
diff --git a/src/extent_mmap.c b/src/extent_mmap.c
index 8d607dc8..17fd1c8f 100644
--- a/src/extent_mmap.c
+++ b/src/extent_mmap.c
@@ -21,8 +21,8 @@ bool	opt_retain =
 void *
 extent_alloc_mmap(void *new_addr, size_t size, size_t alignment, bool *zero,
     bool *commit) {
-	void *ret = pages_map(new_addr, size, ALIGNMENT_CEILING(alignment,
-	    PAGE), commit);
+	assert(alignment == ALIGNMENT_CEILING(alignment, PAGE));
+	void *ret = pages_map(new_addr, size, alignment, commit);
 	if (ret == NULL) {
 		return NULL;
 	}