diff --git a/cores/esp8266/umm_malloc/umm_malloc.h b/cores/esp8266/umm_malloc/umm_malloc.h
index 7f1c05849..0019b0ec5 100644
--- a/cores/esp8266/umm_malloc/umm_malloc.h
+++ b/cores/esp8266/umm_malloc/umm_malloc.h
@@ -12,6 +12,10 @@
 
 #include "umm_malloc_cfg.h"   /* user-dependent */
 
+#ifdef __cplusplus
+extern "C" {
+#endif
+
 typedef struct UMM_HEAP_INFO_t {
   unsigned short int totalEntries;
   unsigned short int usedEntries;
@@ -38,6 +42,9 @@ void umm_free( void *ptr );
 
 size_t umm_free_heap_size( void );
 
+#ifdef __cplusplus
+}
+#endif
 
 /* ------------------------------------------------------------------------ */
 
diff --git a/cores/esp8266/umm_malloc/umm_malloc_cfg.h b/cores/esp8266/umm_malloc/umm_malloc_cfg.h
index 544545a47..87a5a167c 100644
--- a/cores/esp8266/umm_malloc/umm_malloc_cfg.h
+++ b/cores/esp8266/umm_malloc/umm_malloc_cfg.h
@@ -7,7 +7,7 @@
 
 #include <debug.h>
 #ifdef __cplusplus
-#extern "C" {
+extern "C" {
 #endif
 #include "c_types.h"
 #ifdef __cplusplus
diff --git a/tests/.gitignore b/tests/.gitignore
new file mode 100644
index 000000000..7bce08d60
--- /dev/null
+++ b/tests/.gitignore
@@ -0,0 +1,3 @@
+hardware
+tmp
+.env
diff --git a/tests/test_umm_malloc/test_umm_malloc.ino b/tests/test_umm_malloc/test_umm_malloc.ino
new file mode 100644
index 000000000..16348bc70
--- /dev/null
+++ b/tests/test_umm_malloc/test_umm_malloc.ino
@@ -0,0 +1,13 @@
+// test that we can include umm_malloc.h from sketch (#1652)
+#include <umm_malloc/umm_malloc.h>
+
+
+void setup() {
+    Serial.begin(115200);
+    delay(1000);
+    umm_info(NULL, 1);
+}
+
+void loop() {
+
+}