diff --git a/src/config.c b/src/config.c
index a1122d05..5bc6aa2e 100644
--- a/src/config.c
+++ b/src/config.c
@@ -1031,9 +1031,10 @@ void configSetCommand(client *c) {
         if (server.active_defrag_enabled) {
             server.active_defrag_enabled = 0;
             addReplyError(c,
-                "Active defragmentation cannot be enabled: it requires a "
-                "Redis server compiled with a modified Jemalloc like the "
-                "one shipped by default with the Redis source distribution");
+                "-DISABLED Active defragmentation cannot be enabled: it "
+                "requires a Redis server compiled with a modified Jemalloc "
+                "like the one shipped by default with the Redis source "
+                "distribution");
             return;
         }
 #endif
diff --git a/tests/unit/memefficiency.tcl b/tests/unit/memefficiency.tcl
index f9006ace..1796d695 100644
--- a/tests/unit/memefficiency.tcl
+++ b/tests/unit/memefficiency.tcl
@@ -55,31 +55,35 @@ start_server {tags {"defrag"}} {
                 puts "frag $frag"
             }
             assert {$frag >= 1.4}
-            r config set activedefrag yes
+            catch {r config set activedefrag yes} e
+            if {![string match {DISABLED*} $e]} {
+                # Wait for the active defrag to start working (decision once a
+                # second).
+                wait_for_condition 50 100 {
+                    [s active_defrag_running] ne 0
+                } else {
+                    fail "defrag not started."
+                }
 
-            # wait for the active defrag to start working (decision once a second)
-            wait_for_condition 50 100 {
-                [s active_defrag_running] ne 0
+                # Wait for the active defrag to stop working.
+                wait_for_condition 100 100 {
+                    [s active_defrag_running] eq 0
+                } else {
+                    puts [r info memory]
+                    puts [r memory malloc-stats]
+                    fail "defrag didn't stop."
+                }
+
+                # Test the the fragmentation is lower.
+                after 120 ;# serverCron only updates the info once in 100ms
+                set frag [s allocator_frag_ratio]
+                if {$::verbose} {
+                    puts "frag $frag"
+                }
+                assert {$frag < 1.1}
             } else {
-                fail "defrag not started."
+                set _ ""
             }
-
-            # wait for the active defrag to stop working
-            wait_for_condition 100 100 {
-                [s active_defrag_running] eq 0
-            } else {
-                puts [r info memory]
-                puts [r memory malloc-stats]
-                fail "defrag didn't stop."
-            }
-
-            # test the the fragmentation is lower
-            after 120 ;# serverCron only updates the info once in 100ms
-            set frag [s allocator_frag_ratio]
-            if {$::verbose} {
-                puts "frag $frag"
-            }
-            assert {$frag < 1.1}
         } {}
 
         test "Active defrag big keys" {
@@ -150,44 +154,48 @@ start_server {tags {"defrag"}} {
             assert {$frag >= $expected_frag}
             r config set latency-monitor-threshold 5
             r latency reset
-            r config set activedefrag yes
 
-            # wait for the active defrag to start working (decision once a second)
-            wait_for_condition 50 100 {
-                [s active_defrag_running] ne 0
-            } else {
-                fail "defrag not started."
-            }
-
-            # wait for the active defrag to stop working
-            wait_for_condition 500 100 {
-                [s active_defrag_running] eq 0
-            } else {
-                puts [r info memory]
-                puts [r memory malloc-stats]
-                fail "defrag didn't stop."
-            }
-
-            # test the the fragmentation is lower
-            after 120 ;# serverCron only updates the info once in 100ms
-            set frag [s allocator_frag_ratio]
-            set max_latency 0
-            foreach event [r latency latest] {
-                lassign $event eventname time latency max
-                if {$eventname == "active-defrag-cycle"} {
-                    set max_latency $max
+            catch {r config set activedefrag yes} e
+            if {![string match {DISABLED*} $e]} {
+                # wait for the active defrag to start working (decision once a second)
+                wait_for_condition 50 100 {
+                    [s active_defrag_running] ne 0
+                } else {
+                    fail "defrag not started."
                 }
+
+                # wait for the active defrag to stop working
+                wait_for_condition 500 100 {
+                    [s active_defrag_running] eq 0
+                } else {
+                    puts [r info memory]
+                    puts [r memory malloc-stats]
+                    fail "defrag didn't stop."
+                }
+
+                # test the the fragmentation is lower
+                after 120 ;# serverCron only updates the info once in 100ms
+                set frag [s allocator_frag_ratio]
+                set max_latency 0
+                foreach event [r latency latest] {
+                    lassign $event eventname time latency max
+                    if {$eventname == "active-defrag-cycle"} {
+                        set max_latency $max
+                    }
+                }
+                if {$::verbose} {
+                    puts "frag $frag"
+                    puts "max latency $max_latency"
+                    puts [r latency latest]
+                    puts [r latency history active-defrag-cycle]
+                }
+                assert {$frag < 1.1}
+                # due to high fragmentation, 10hz, and active-defrag-cycle-max set to 75,
+                # we expect max latency to be not much higher than 75ms
+                assert {$max_latency <= 80}
+            } else {
+                set _ ""
             }
-            if {$::verbose} {
-                puts "frag $frag"
-                puts "max latency $max_latency"
-                puts [r latency latest]
-                puts [r latency history active-defrag-cycle]
-            }
-            assert {$frag < 1.1}
-            # due to high fragmentation, 10hz, and active-defrag-cycle-max set to 75,
-            # we expect max latency to be not much higher than 75ms
-            assert {$max_latency <= 80}
         } {}
     }
 }