diff --git a/tools/jam/src/build.jam b/tools/jam/src/build.jam
index e30e854..7b397a3 100644
--- a/tools/jam/src/build.jam
+++ b/tools/jam/src/build.jam
@@ -2,6 +2,20 @@
 #~ Distributed under the Boost Software License, Version 1.0.
 #~ (See accompanying file LICENSE_1_0.txt or http://www.boost.org/LICENSE_1_0.txt)
 
+# Clean env vars of any "extra" empty values.
+for local v in ARGV CC CFLAGS
+{
+	local values ;
+	for local x in $($(v))
+	{
+		if $(x) != ""
+		{
+			values += $(x) ;
+		}
+	}
+	$(v) = $(values) ;
+}
+
 # Platform related specifics.
 if $(NT) { rule .path { return "$(<:J=\\)" ; } ./ = "/" ; }
 else if $(OS2) { rule .path { return "$(<:J=\\)" ; } ./ = "/" ; }