diff --git a/opengl/libagl/egl.cpp b/opengl/libagl/egl.cpp
index 5b90bf0..3b4c041 100644
--- a/opengl/libagl/egl.cpp
+++ b/opengl/libagl/egl.cpp
@@ -1055,8 +1055,12 @@
 {
     if (egl_display_t::is_valid(dpy) == EGL_FALSE)
         return setError(EGL_BAD_DISPLAY, EGL_FALSE);
+    
+    if (ggl_unlikely(num_config==0)) {
+        return setError(EGL_BAD_PARAMETER, EGL_FALSE);
+    }
 
-    if (ggl_unlikely(configs==0 || attrib_list==0)) {
+    if (ggl_unlikely(attrib_list==0)) {
         *num_config = 0;
         return EGL_TRUE;
     }
@@ -1102,11 +1106,19 @@
     // return the configurations found
     int n=0;
     if (possibleMatch) {
-        for (int i=0 ; config_size && i<numConfigs ; i++) {
-            if (possibleMatch & (1<<i)) {
-               *configs++ = (EGLConfig)i;
-                config_size--;
-                n++;
+        if (configs) {
+            for (int i=0 ; config_size && i<numConfigs ; i++) {
+                if (possibleMatch & (1<<i)) {
+                    *configs++ = (EGLConfig)i;
+                    config_size--;
+                    n++;
+                }
+            }
+        } else {
+            for (int i=0 ; i<numConfigs ; i++) {
+                if (possibleMatch & (1<<i)) {
+                    n++;
+                }
             }
         }
     }
diff --git a/opengl/libs/EGL/egl.cpp b/opengl/libs/EGL/egl.cpp
index 687c8bc..0b4bcce 100644
--- a/opengl/libs/EGL/egl.cpp
+++ b/opengl/libs/EGL/egl.cpp
@@ -725,9 +725,8 @@
     egl_display_t const * const dp = get_display(dpy);
     if (!dp) return setError(EGL_BAD_DISPLAY, EGL_FALSE);
 
-    if (configs == 0) {
-        *num_config = 0;
-        return EGL_TRUE;
+    if (num_config==0) {
+        return setError(EGL_BAD_PARAMETER, EGL_FALSE);
     }
 
     EGLint n;
@@ -784,7 +783,9 @@
             if (res && n>0) {
                 // n has to be 0 or 1, by construction, and we already know
                 // which config it will return (since there can be only one).
-                configs[0] = MAKE_CONFIG(i, index);
+                if (configs) {
+                    configs[0] = MAKE_CONFIG(i, index);
+                }
                 *num_config = 1;
             }
         }
@@ -798,19 +799,23 @@
         if (cnx->dso) {
             if (cnx->hooks->egl.eglChooseConfig(
                     dp->dpys[i], attrib_list, configs, config_size, &n)) {
-                // now we need to convert these client EGLConfig to our
-                // internal EGLConfig format. This is done in O(n log n).
-                for (int j=0 ; j<n ; j++) {
-                    int index = binarySearch<EGLConfig>(
-                            dp->configs[i], 0, dp->numConfigs[i]-1, configs[j]);
-                    if (index >= 0) {
-                        configs[j] = MAKE_CONFIG(i, index);
-                    } else {
-                        return setError(EGL_BAD_CONFIG, EGL_FALSE);
+                if (configs) {
+                    // now we need to convert these client EGLConfig to our
+                    // internal EGLConfig format. This is done in O(n log n).
+                    for (int j=0 ; j<n ; j++) {
+                        int index = binarySearch<EGLConfig>(
+                                dp->configs[i], 0, dp->numConfigs[i]-1, configs[j]);
+                        if (index >= 0) {
+                            if (configs) {
+                                configs[j] = MAKE_CONFIG(i, index);
+                            }
+                        } else {
+                            return setError(EGL_BAD_CONFIG, EGL_FALSE);
+                        }
                     }
+                    configs += n;
+                    config_size -= n;
                 }
-                configs += n;
-                config_size -= n;
                 *num_config += n;
                 res = EGL_TRUE;
             }