diff --git a/ChangeLog b/ChangeLog
index cb483886a..c5041cd4e 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -3,6 +3,9 @@
 	* configure.in:
 	Change to version 17
 
+	* src/include/ngspice.h:
+	include <errno.h> for Tcl version of perror
+
 2004-06-22 Adrian Dawe <adrian.dawe@multigig.com>
 
 	* src/pkgIndex.tcl.in  src/spicepp.pl  src/spicepp.tcl  src/spicewish 
diff --git a/src/include/ngspice.h b/src/include/ngspice.h
index 519a928c4..6404e17f5 100644
--- a/src/include/ngspice.h
+++ b/src/include/ngspice.h
@@ -174,6 +174,8 @@ extern int ARCHsize;	/* Total number of processes */
 
 #ifdef TCL_MODULE
 
+#include <errno.h>
+
 extern int tcl_printf(const char *format, ...);
 extern int tcl_fprintf(FILE *f, const char *format, ...);