diff --git a/src/gtk/utilsgtk.cpp b/src/gtk/utilsgtk.cpp
index 07ca4f5658..2befc47dc3 100644
--- a/src/gtk/utilsgtk.cpp
+++ b/src/gtk/utilsgtk.cpp
@@ -37,7 +37,11 @@
 
 #ifdef __SOLARIS__
 // somehow missing from sys/wait.h but in the system's docs
-pid_t wait4(pid_t pid, int *statusp, int options, struct rusage *rusage);   
+extern "C"
+{
+   pid_t wait4(pid_t pid, int *statusp, int options, struct rusage
+               *rusage);
+}
 #endif
 
 //------------------------------------------------------------------------
diff --git a/src/gtk1/utilsgtk.cpp b/src/gtk1/utilsgtk.cpp
index 07ca4f5658..2befc47dc3 100644
--- a/src/gtk1/utilsgtk.cpp
+++ b/src/gtk1/utilsgtk.cpp
@@ -37,7 +37,11 @@
 
 #ifdef __SOLARIS__
 // somehow missing from sys/wait.h but in the system's docs
-pid_t wait4(pid_t pid, int *statusp, int options, struct rusage *rusage);   
+extern "C"
+{
+   pid_t wait4(pid_t pid, int *statusp, int options, struct rusage
+               *rusage);
+}
 #endif
 
 //------------------------------------------------------------------------