diff --git a/Makefile.include b/Makefile.include
index d3dc8bddf..6c3418ef0 100644
--- a/Makefile.include
+++ b/Makefile.include
@@ -76,7 +76,7 @@ MODULES += os os/sys os/dev os/lib os/services
 
 # Automatically include project-conf.h if found
 ifneq ("$(wildcard project-conf.h)","")
-CFLAGS += -DPROJECT_CONF_H=\"project-conf.h\"
+CFLAGS += -DPROJECT_CONF_PATH=\"project-conf.h\"
 endif
 
 # Configure MAC layer
diff --git a/arch/platform/cc2538dk/contiki-conf.h b/arch/platform/cc2538dk/contiki-conf.h
index e37b8b32c..cad72f1ca 100644
--- a/arch/platform/cc2538dk/contiki-conf.h
+++ b/arch/platform/cc2538dk/contiki-conf.h
@@ -12,9 +12,9 @@
 #include <string.h>
 /*---------------------------------------------------------------------------*/
 /* Include Project Specific conf */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 /*---------------------------------------------------------------------------*/
 /**
  * \name Compiler configuration and platform-specific type definitions
diff --git a/arch/platform/cooja/contiki-conf.h b/arch/platform/cooja/contiki-conf.h
index a5ca79f90..b15ea4636 100644
--- a/arch/platform/cooja/contiki-conf.h
+++ b/arch/platform/cooja/contiki-conf.h
@@ -138,10 +138,9 @@ typedef uint64_t rtimer_clock_t;
 #define NETSTACK_RADIO_MAX_PAYLOAD_LEN 125
 
 /* include the project config */
-/* PROJECT_CONF_H might be defined in the project Makefile */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 
 
 #endif /* CONTIKI_CONF_H_ */
diff --git a/arch/platform/jn516x/contiki-conf.h b/arch/platform/jn516x/contiki-conf.h
index 1f6cd7d2f..f464d8773 100644
--- a/arch/platform/jn516x/contiki-conf.h
+++ b/arch/platform/jn516x/contiki-conf.h
@@ -50,9 +50,8 @@
 #endif /* CCM_STAR_CONF */
 
 /* include the project config */
-/* PROJECT_CONF_H might be defined in the project Makefile */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 
 #endif /* CONTIKI_CONF_H_ */
diff --git a/arch/platform/native/contiki-conf.h b/arch/platform/native/contiki-conf.h
index 81bfc1815..9d24dace9 100644
--- a/arch/platform/native/contiki-conf.h
+++ b/arch/platform/native/contiki-conf.h
@@ -91,9 +91,8 @@ typedef unsigned long clock_time_t;
 int strcasecmp(const char*, const char*);
 
 /* include the project config */
-/* PROJECT_CONF_H might be defined in the project Makefile */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 
 #endif /* CONTIKI_CONF_H_ */
diff --git a/arch/platform/nrf52dk/contiki-conf.h b/arch/platform/nrf52dk/contiki-conf.h
index 55b40ebb8..c283f7231 100644
--- a/arch/platform/nrf52dk/contiki-conf.h
+++ b/arch/platform/nrf52dk/contiki-conf.h
@@ -43,9 +43,9 @@
 #include <stdint.h>
 /*---------------------------------------------------------------------------*/
 /* Include Project Specific conf */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 /*---------------------------------------------------------------------------*/
 /* Include platform peripherals configuration */
 #include "platform-conf.h"
diff --git a/arch/platform/openmote-cc2538/contiki-conf.h b/arch/platform/openmote-cc2538/contiki-conf.h
index a03cd245a..d00836326 100644
--- a/arch/platform/openmote-cc2538/contiki-conf.h
+++ b/arch/platform/openmote-cc2538/contiki-conf.h
@@ -51,9 +51,9 @@
 #include <string.h>
 /*---------------------------------------------------------------------------*/
 /* Include Project Specific conf */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 /*---------------------------------------------------------------------------*/
 /**
  * \name Compiler configuration and platform-specific type definitions
diff --git a/arch/platform/sky/contiki-conf.h b/arch/platform/sky/contiki-conf.h
index a513a14f4..6bce536ec 100644
--- a/arch/platform/sky/contiki-conf.h
+++ b/arch/platform/sky/contiki-conf.h
@@ -34,9 +34,8 @@
 #endif /* AES_128_CONF */
 
 /* include the project config */
-/* PROJECT_CONF_H might be defined in the project Makefile */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 
 #endif /* CONTIKI_CONF_H */
diff --git a/arch/platform/srf06-cc26xx/contiki-conf.h b/arch/platform/srf06-cc26xx/contiki-conf.h
index 4f464809a..7cfc46801 100644
--- a/arch/platform/srf06-cc26xx/contiki-conf.h
+++ b/arch/platform/srf06-cc26xx/contiki-conf.h
@@ -40,9 +40,9 @@
 #include <stdint.h>
 /*---------------------------------------------------------------------------*/
 /* Include Project Specific conf */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 /*---------------------------------------------------------------------------*/
 /**
  * \name Network Stack Configuration
diff --git a/arch/platform/zoul/contiki-conf.h b/arch/platform/zoul/contiki-conf.h
index 99a88ed52..93699c2e8 100644
--- a/arch/platform/zoul/contiki-conf.h
+++ b/arch/platform/zoul/contiki-conf.h
@@ -49,9 +49,9 @@
 #include <string.h>
 /*---------------------------------------------------------------------------*/
 /* Include Project Specific conf */
-#ifdef PROJECT_CONF_H
-#include PROJECT_CONF_H
-#endif /* PROJECT_CONF_H */
+#ifdef PROJECT_CONF_PATH
+#include PROJECT_CONF_PATH
+#endif /* PROJECT_CONF_PATH */
 /*---------------------------------------------------------------------------*/
 /**
  * \name Compiler configuration and platform-specific type definitions
diff --git a/os/lib/heapmem.c b/os/lib/heapmem.c
index e450cfdd1..54394ff01 100644
--- a/os/lib/heapmem.c
+++ b/os/lib/heapmem.c
@@ -48,9 +48,9 @@
 #define PRINTF(...)
 #endif
 
-#ifdef PROJECT_CONF_H
+#ifdef PROJECT_CONF_PATH
 /* Load the heapmem configuration from a project configuration file. */
-#include PROJECT_CONF_H
+#include PROJECT_CONF_PATH
 #endif
 
 #include <stdint.h>