diff --git a/makefile b/makefile
index c05ed593..12735414 100644
--- a/makefile
+++ b/makefile
@@ -577,21 +577,21 @@ ifeq (${WIN32},)  #*nix Environments (&& cygwin)
   endif
   ifneq (,$(call find_include,dlfcn))
     ifneq (,$(call find_lib,dl))
-      OS_CCDEFS += -DHAVE_DLOPEN=$(LIBSOEXT)
+      OS_CCDEFS += -DSIM_HAVE_DLOPEN=$(LIBSOEXT)
       OS_LDFLAGS += -ldl
       $(info using libdl: $(call find_lib,dl) $(call find_include,dlfcn))
     else
       ifneq (,$(findstring BSD,$(OSTYPE))$(findstring AIX,$(OSTYPE))$(findstring Haiku,$(OSTYPE)))
-        OS_CCDEFS += -DHAVE_DLOPEN=so
+        OS_CCDEFS += -DSIM_HAVE_DLOPEN=so
         $(info using libdl: $(call find_include,dlfcn))
       else
         ifneq (,$(call find_lib,dld))
-          OS_CCDEFS += -DHAVE_DLOPEN=$(LIBSOEXT)
+          OS_CCDEFS += -DSIM_HAVE_DLOPEN=$(LIBSOEXT)
           OS_LDFLAGS += -ldld
           $(info using libdld: $(call find_lib,dld) $(call find_include,dlfcn))
         else
           ifeq (Darwin,$(OSTYPE))
-            OS_CCDEFS += -DHAVE_DLOPEN=dylib
+            OS_CCDEFS += -DSIM_HAVE_DLOPEN=dylib
             $(info using macOS dlopen with .dylib)
           endif
         endif
diff --git a/scp.c b/scp.c
index 2987072e..3497c8ff 100644
--- a/scp.c
+++ b/scp.c
@@ -238,7 +238,7 @@
 #endif
 #include <setjmp.h>
 
-#if defined(HAVE_DLOPEN)                                /* Dynamic Readline support */
+#if defined(SIM_HAVE_DLOPEN)                                /* Dynamic Readline support */
 #include <dlfcn.h>
 #endif
 
@@ -10091,7 +10091,7 @@ return read_line_p (NULL, cptr, size, stream);
 char *read_line_p (const char *prompt, char *cptr, int32 size, FILE *stream)
 {
 char *tptr;
-#if defined(HAVE_DLOPEN)
+#if defined(SIM_HAVE_DLOPEN)
 static int initialized = 0;
 typedef char *(*readline_func)(const char *);
 static readline_func p_readline = NULL;
@@ -10104,15 +10104,15 @@ if (prompt && (!initialized)) {
 
 #define S__STR_QUOTE(tok) #tok
 #define S__STR(tok) S__STR_QUOTE(tok)
-    handle = dlopen("libncurses." S__STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
-    handle = dlopen("libcurses." S__STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
-    handle = dlopen("libreadline." S__STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    handle = dlopen("libncurses." S__STR(SIM_HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    handle = dlopen("libcurses." S__STR(SIM_HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    handle = dlopen("libreadline." S__STR(SIM_HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
     if (!handle)
-        handle = dlopen("libreadline." S__STR(HAVE_DLOPEN) ".7", RTLD_NOW|RTLD_GLOBAL);
+        handle = dlopen("libreadline." S__STR(SIM_HAVE_DLOPEN) ".7", RTLD_NOW|RTLD_GLOBAL);
     if (!handle)
-        handle = dlopen("libreadline." S__STR(HAVE_DLOPEN) ".6", RTLD_NOW|RTLD_GLOBAL);
+        handle = dlopen("libreadline." S__STR(SIM_HAVE_DLOPEN) ".6", RTLD_NOW|RTLD_GLOBAL);
     if (!handle)
-        handle = dlopen("libreadline." S__STR(HAVE_DLOPEN) ".5", RTLD_NOW|RTLD_GLOBAL);
+        handle = dlopen("libreadline." S__STR(SIM_HAVE_DLOPEN) ".5", RTLD_NOW|RTLD_GLOBAL);
     if (handle) {
         p_readline = (readline_func)((size_t)dlsym(handle, "readline"));
         p_add_history = (add_history_func)((size_t)dlsym(handle, "add_history"));
@@ -10165,7 +10165,7 @@ if ((*cptr == ';') || (*cptr == '#')) {                 /* ignore comment */
     *cptr = 0;
     }
 
-#if defined (HAVE_DLOPEN)
+#if defined (SIM_HAVE_DLOPEN)
 if (prompt && p_add_history && *cptr)                   /* Save non blank lines in history */
     p_add_history (cptr);
 #endif
diff --git a/sim_disk.c b/sim_disk.c
index 57214ae3..c866a127 100644
--- a/sim_disk.c
+++ b/sim_disk.c
@@ -5222,7 +5222,7 @@ if (UuidCreate_c)
 else
     _rand_uuid_gen (uuidaddr);
 }
-#elif defined (HAVE_DLOPEN)
+#elif defined (SIM_HAVE_DLOPEN)
 #include <dlfcn.h>
 
 static void
@@ -5233,7 +5233,7 @@ void *handle;
 
 #define S__STR_QUOTE(tok) #tok
 #define S__STR(tok) S__STR_QUOTE(tok)
-    handle = dlopen("libuuid." S__STR(HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
+    handle = dlopen("libuuid." S__STR(SIM_HAVE_DLOPEN), RTLD_NOW|RTLD_GLOBAL);
     if (handle)
         uuid_generate_c = (void (*)(void *))((size_t)dlsym(handle, "uuid_generate"));
     if (uuid_generate_c)
diff --git a/sim_ether.c b/sim_ether.c
index 7fd2883e..bfee3645 100644
--- a/sim_ether.c
+++ b/sim_ether.c
@@ -1225,11 +1225,11 @@ extern "C" {
 #include <winreg.h>
 #endif
 
-#ifdef HAVE_DLOPEN
+#ifdef SIM_HAVE_DLOPEN
 #include <dlfcn.h>
 #endif
 
-#if defined(USE_SHARED) && (defined(_WIN32) || defined(HAVE_DLOPEN))
+#if defined(USE_SHARED) && (defined(_WIN32) || defined(SIM_HAVE_DLOPEN))
 /* Dynamic DLL loading technique and modified source comes from
    Etherial/WireShark capture_pcap.c */
 
@@ -1249,7 +1249,7 @@ static const char* lib_name =
 #elif defined(__APPLE__)
                           "/usr/lib/libpcap.A.dylib";
 #else
-                          "libpcap." __STR(HAVE_DLOPEN);
+                          "libpcap." __STR(SIM_HAVE_DLOPEN);
 #endif
 
 static char no_pcap[PCAP_ERRBUF_SIZE] =
@@ -1258,7 +1258,7 @@ static char no_pcap[PCAP_ERRBUF_SIZE] =
 #elif defined(__APPLE__)
     "/usr/lib/libpcap.A.dylib failed to load, install libpcap to use pcap networking";
 #else
-    "libpcap." __STR(HAVE_DLOPEN) " failed to load, install libpcap to use pcap networking";
+    "libpcap." __STR(SIM_HAVE_DLOPEN) " failed to load, install libpcap to use pcap networking";
 #endif
 #undef __STR
 #undef __STR_QUOTE
@@ -1529,7 +1529,7 @@ int pcap_setnonblock(pcap_t* a, int nonblock, char *errbuf) {
     return 0;
   }
 }
-#endif /* defined(USE_SHARED) && (defined(_WIN32) || defined(HAVE_DLOPEN)) */
+#endif /* defined(USE_SHARED) && (defined(_WIN32) || defined(SIM_HAVE_DLOPEN)) */
 
 /* Some platforms have always had pcap_sendpacket */
 #if defined(_WIN32) || defined(__VMS)
diff --git a/sim_ether.h b/sim_ether.h
index f3edab8d..5b5c9128 100644
--- a/sim_ether.h
+++ b/sim_ether.h
@@ -124,8 +124,8 @@ extern "C" {
 #if defined(USE_NETWORK) && defined(USE_SHARED)
 #undef USE_SHARED
 #endif
-/* USE_SHARED only works on Windows or if HAVE_DLOPEN */
-#if defined(USE_SHARED) && !defined(_WIN32) && !defined(HAVE_DLOPEN)
+/* USE_SHARED only works on Windows or if SIM_HAVE_DLOPEN */
+#if defined(USE_SHARED) && !defined(_WIN32) && !defined(SIM_HAVE_DLOPEN)
 #undef USE_SHARED
 #endif
 
diff --git a/sim_sock.c b/sim_sock.c
index 6f357cc3..9b291c92 100644
--- a/sim_sock.c
+++ b/sim_sock.c
@@ -55,7 +55,7 @@ extern "C" {
 #include <ws2tcpip.h>
 #endif
 
-#ifdef HAVE_DLOPEN
+#ifdef SIM_HAVE_DLOPEN
 #include <dlfcn.h>
 #endif