diff --git a/include/jemalloc/internal/arena_structs.h b/include/jemalloc/internal/arena_structs.h
index 2d5c5680..fde540af 100644
--- a/include/jemalloc/internal/arena_structs.h
+++ b/include/jemalloc/internal/arena_structs.h
@@ -197,10 +197,4 @@ struct arena_tdata_s {
 	ticker_t		decay_ticker;
 };
 
-/* Used to pass rtree lookup context down the path. */
-struct alloc_ctx_s {
-	szind_t szind;
-	bool slab;
-};
-
 #endif /* JEMALLOC_INTERNAL_ARENA_STRUCTS_B_H */
diff --git a/include/jemalloc/internal/arena_types.h b/include/jemalloc/internal/arena_types.h
index 369dff06..b13d8a05 100644
--- a/include/jemalloc/internal/arena_types.h
+++ b/include/jemalloc/internal/arena_types.h
@@ -12,7 +12,6 @@
 typedef struct arena_decay_s arena_decay_t;
 typedef struct arena_s arena_t;
 typedef struct arena_tdata_s arena_tdata_t;
-typedef struct alloc_ctx_s alloc_ctx_t;
 
 typedef enum {
 	percpu_arena_mode_names_base   = 0, /* Used for options processing. */
diff --git a/include/jemalloc/internal/emap.h b/include/jemalloc/internal/emap.h
index 9e3b415c..4588daf9 100644
--- a/include/jemalloc/internal/emap.h
+++ b/include/jemalloc/internal/emap.h
@@ -11,6 +11,13 @@ struct emap_s {
 	mutex_pool_t mtx_pool;
 };
 
+/* Used to pass rtree lookup context down the path. */
+typedef struct alloc_ctx_t alloc_ctx_t;
+struct alloc_ctx_t {
+	szind_t szind;
+	bool slab;
+};
+
 extern emap_t emap_global;
 
 bool emap_init(emap_t *emap);
@@ -127,4 +134,15 @@ emap_lookup(tsdn_t *tsdn, emap_t *emap, const void *ptr) {
 	    true);
 }
 
+/* Fills in alloc_ctx with the info in the map. */
+JEMALLOC_ALWAYS_INLINE void
+emap_alloc_info_lookup(tsdn_t *tsdn, emap_t *emap, void *ptr,
+    alloc_ctx_t *alloc_ctx) {
+	rtree_ctx_t rtree_ctx_fallback;
+	rtree_ctx_t *rtree_ctx = tsdn_rtree_ctx(tsdn, &rtree_ctx_fallback);
+
+	rtree_szind_slab_read(tsdn, &emap->rtree, rtree_ctx, (uintptr_t)ptr,
+	    true, &alloc_ctx->szind, &alloc_ctx->slab);
+}
+
 #endif /* JEMALLOC_INTERNAL_EMAP_H */
diff --git a/src/jemalloc.c b/src/jemalloc.c
index 2b4cd277..d0af5da5 100644
--- a/src/jemalloc.c
+++ b/src/jemalloc.c
@@ -2568,9 +2568,7 @@ ifree(tsd_t *tsd, void *ptr, tcache_t *tcache, bool slow_path) {
 	assert(malloc_initialized() || IS_INITIALIZER);
 
 	alloc_ctx_t alloc_ctx;
-	rtree_ctx_t *rtree_ctx = tsd_rtree_ctx(tsd);
-	rtree_szind_slab_read(tsd_tsdn(tsd), &emap_global.rtree, rtree_ctx,
-	    (uintptr_t)ptr, true, &alloc_ctx.szind, &alloc_ctx.slab);
+	emap_alloc_info_lookup(tsd_tsdn(tsd), &emap_global, ptr, &alloc_ctx);
 	assert(alloc_ctx.szind != SC_NSIZES);
 
 	size_t usize = sz_index2size(alloc_ctx.szind);
@@ -2601,57 +2599,55 @@ isfree(tsd_t *tsd, void *ptr, size_t usize, tcache_t *tcache, bool slow_path) {
 	assert(ptr != NULL);
 	assert(malloc_initialized() || IS_INITIALIZER);
 
-	alloc_ctx_t alloc_ctx, *ctx;
+	alloc_ctx_t alloc_ctx;
 	if (!config_prof) {
-		/* Means usize will be used to determine szind. */
-		ctx = NULL;
+		alloc_ctx.szind = sz_size2index(usize);
+		alloc_ctx.slab = (alloc_ctx.szind < SC_NBINS);
 	} else {
 		if (likely(!prof_sample_aligned(ptr))) {
-			ctx = &alloc_ctx;
 			/*
 			 * When the ptr is not page aligned, it was not sampled.
 			 * usize can be trusted to determine szind and slab.
 			 */
-			ctx->szind = sz_size2index(usize);
+			alloc_ctx.szind = sz_size2index(usize);
 			if (config_cache_oblivious) {
-				ctx->slab = (ctx->szind < SC_NBINS);
+				alloc_ctx.slab = (alloc_ctx.szind < SC_NBINS);
 			} else {
 				/* Non page aligned must be slab allocated. */
-				ctx->slab = true;
+				alloc_ctx.slab = true;
 			}
 			if (config_debug) {
 				alloc_ctx_t dbg_ctx;
-				rtree_ctx_t *rtree_ctx = tsd_rtree_ctx(tsd);
-				rtree_szind_slab_read(tsd_tsdn(tsd),
-				    &emap_global.rtree, rtree_ctx,
-				    (uintptr_t)ptr, true, &dbg_ctx.szind,
-				    &dbg_ctx.slab);
-				assert(dbg_ctx.szind == ctx->szind);
-				assert(dbg_ctx.slab == ctx->slab);
+				emap_alloc_info_lookup(tsd_tsdn(tsd),
+				    &emap_global, ptr, &dbg_ctx);
+				assert(dbg_ctx.szind == alloc_ctx.szind);
+				assert(dbg_ctx.slab == alloc_ctx.slab);
 			}
 		} else if (opt_prof) {
-			ctx = &alloc_ctx;
-			rtree_ctx_t *rtree_ctx = tsd_rtree_ctx(tsd);
-			rtree_szind_slab_read(tsd_tsdn(tsd), &emap_global.rtree,
-			    rtree_ctx, (uintptr_t)ptr, true, &ctx->szind,
-			    &ctx->slab);
-			/* Small alloc may have !slab (sampled). */
-			bool sz_correct = (ctx->szind == sz_size2index(usize));
-			if (config_opt_safety_checks && !sz_correct) {
-				safety_check_fail_sized_dealloc(true);
+			emap_alloc_info_lookup(tsd_tsdn(tsd), &emap_global,
+			    ptr, &alloc_ctx);
+
+			if (config_opt_safety_checks) {
+				/* Small alloc may have !slab (sampled). */
+				if (alloc_ctx.szind != sz_size2index(usize)) {
+					safety_check_fail_sized_dealloc(true);
+				}
 			}
 		} else {
-			ctx = NULL;
+			alloc_ctx.szind = sz_size2index(usize);
+			alloc_ctx.slab = (alloc_ctx.szind < SC_NBINS);
 		}
 	}
 
 	if (config_prof && opt_prof) {
-		prof_free(tsd, ptr, usize, ctx);
+		prof_free(tsd, ptr, usize, &alloc_ctx);
 	}
 	if (likely(!slow_path)) {
-		isdalloct(tsd_tsdn(tsd), ptr, usize, tcache, ctx, false);
+		isdalloct(tsd_tsdn(tsd), ptr, usize, tcache, &alloc_ctx,
+		    false);
 	} else {
-		isdalloct(tsd_tsdn(tsd), ptr, usize, tcache, ctx, true);
+		isdalloct(tsd_tsdn(tsd), ptr, usize, tcache, &alloc_ctx,
+		    true);
 	}
 	thread_dalloc_event(tsd, usize);
 }