diff --git a/m4/ipopt.m4 b/m4/ipopt.m4
index 5a167ae009d7fb53ddf8c60bab55ba0b4380d3ec..78f082b0cc063264b7648ffc1e669ca0d3957d45 100644
--- a/m4/ipopt.m4
+++ b/m4/ipopt.m4
@@ -31,7 +31,7 @@ AS_IF([test x$with_ipopt != xno], [
     IPOPT_LIB_PATH="$IPOPTROOT/lib"
 
     # Check for ipopt and set IPOPT_*
-    export PKG_CONFIG_PATH="$PKG_CONFIG_PATH:$IPOPT_LIB_PATH/pkgconfig"
+    export PKG_CONFIG_PATH="$IPOPT_LIB_PATH/pkgconfig:$PKG_CONFIG_PATH"
     PKG_CHECK_MODULES([IPOPT], [ipopt], [
 	HAVE_IPOPT="1"
     ], [ dnl default rule would fail