diff --git a/modules/libcom/src/osi/os/Linux/osdgetexec.c b/modules/libcom/src/osi/os/Linux/osdgetexec.c
index cba5d78a8..f79906fb7 100644
--- a/modules/libcom/src/osi/os/Linux/osdgetexec.c
+++ b/modules/libcom/src/osi/os/Linux/osdgetexec.c
@@ -7,6 +7,10 @@
 #define epicsExportSharedSymbols
 #include <osiFileName.h>
 
+#ifndef PATH_MAX
+#  define PATH_MAX 100
+#endif
+
 char *epicsGetExecName(void)
 {
     size_t max = PATH_MAX;