diff --git a/src/extent.c b/src/extent.c
index 4b927191..118c8785 100644
--- a/src/extent.c
+++ b/src/extent.c
@@ -916,15 +916,20 @@ extent_try_coalesce_impl(tsdn_t *tsdn, pac_t *pac, ehooks_t *ehooks,
 		size_t   max_next_neighbor = max_size > edata_size_get(edata)
 		      ? max_size - edata_size_get(edata)
 		      : 0;
-		if (next != NULL && edata_size_get(next) <= max_next_neighbor) {
-			if (!extent_coalesce(
-			        tsdn, pac, ehooks, ecache, edata, next, true)) {
-				if (ecache->delay_coalesce) {
-					/* Do minimal coalescing. */
-					*coalesced = true;
-					return edata;
+		if (next != NULL) {
+			if (edata_size_get(next) > max_next_neighbor) {
+				emap_release_edata(
+				    tsdn, pac->emap, next, ecache->state);
+			} else {
+				if (!extent_coalesce(tsdn, pac, ehooks, ecache,
+				        edata, next, true)) {
+					if (ecache->delay_coalesce) {
+						/* Do minimal coalescing. */
+						*coalesced = true;
+						return edata;
+					}
+					again = true;
 				}
-				again = true;
 			}
 		}
 
@@ -934,16 +939,21 @@ extent_try_coalesce_impl(tsdn_t *tsdn, pac_t *pac, ehooks_t *ehooks,
 		size_t   max_prev_neighbor = max_size > edata_size_get(edata)
 		      ? max_size - edata_size_get(edata)
 		      : 0;
-		if (prev != NULL && edata_size_get(prev) <= max_prev_neighbor) {
-			if (!extent_coalesce(tsdn, pac, ehooks, ecache, edata,
-			        prev, false)) {
-				edata = prev;
-				if (ecache->delay_coalesce) {
-					/* Do minimal coalescing. */
-					*coalesced = true;
-					return edata;
+		if (prev != NULL) {
+			if (edata_size_get(prev) > max_prev_neighbor) {
+				emap_release_edata(
+				    tsdn, pac->emap, prev, ecache->state);
+			} else {
+				if (!extent_coalesce(tsdn, pac, ehooks, ecache,
+				        edata, prev, false)) {
+					edata = prev;
+					if (ecache->delay_coalesce) {
+						/* Do minimal coalescing. */
+						*coalesced = true;
+						return edata;
+					}
+					again = true;
 				}
-				again = true;
 			}
 		}
 	} while (again);
diff --git a/test/unit/pa.c b/test/unit/pa.c
index 8552225f..c1562d7b 100644
--- a/test/unit/pa.c
+++ b/test/unit/pa.c
@@ -121,7 +121,52 @@ TEST_BEGIN(test_alloc_free_purge_thds) {
 }
 TEST_END
 
+TEST_BEGIN(test_failed_coalesce_releases_neighbor) {
+	test_skip_if(!maps_coalesce);
+
+	test_data_t *test_data = init_test_data(-1, -1);
+	size_t old_lg_extent_max_active_fit = opt_lg_extent_max_active_fit;
+	opt_lg_extent_max_active_fit = 0;
+
+	bool     deferred_work_generated = false;
+	size_t   unit = SC_LARGE_MINCLASS;
+	size_t   alloc_size = 4 * unit;
+	edata_t *edata = pa_alloc(TSDN_NULL, &test_data->shard, alloc_size,
+	    PAGE,
+	    /* slab */ false, sz_size2index(alloc_size), /* zero */ false,
+	    /* guarded */ false, &deferred_work_generated);
+	expect_ptr_not_null(edata, "Unexpected pa_alloc() failure");
+
+	void *tail_addr = (void *)((uintptr_t)edata_base_get(edata) + unit);
+	expect_false(pa_shrink(TSDN_NULL, &test_data->shard, edata, alloc_size,
+	                 unit, sz_size2index(unit), &deferred_work_generated),
+	    "Unexpected pa_shrink() failure");
+
+	edata_t *tail = emap_edata_lookup(
+	    TSDN_NULL, &test_data->emap, tail_addr);
+	expect_ptr_not_null(tail, "Expected dirty tail extent after shrink");
+	expect_ptr_eq(
+	    edata_base_get(tail), tail_addr, "Unexpected tail extent address");
+	expect_zu_eq(
+	    edata_size_get(tail), 3 * unit, "Unexpected tail extent size");
+	expect_d_eq(edata_state_get(tail), extent_state_dirty,
+	    "Expected tail extent to start dirty");
+
+	pa_dalloc(
+	    TSDN_NULL, &test_data->shard, edata, &deferred_work_generated);
+
+	tail = emap_edata_lookup(TSDN_NULL, &test_data->emap, tail_addr);
+	expect_ptr_not_null(
+	    tail, "Expected oversized dirty neighbor to remain discoverable");
+	expect_d_eq(edata_state_get(tail), extent_state_dirty,
+	    "Failed coalesce must release oversized dirty neighbor");
+
+	opt_lg_extent_max_active_fit = old_lg_extent_max_active_fit;
+}
+TEST_END
+
 int
 main(void) {
-	return test(test_alloc_free_purge_thds);
+	return test(
+	    test_alloc_free_purge_thds, test_failed_coalesce_releases_neighbor);
 }