diff --git a/result/schemas/582906-1_0_0 b/result/schemas/582906-1_0_0
new file mode 100644
index 00000000..e1abbf58
--- /dev/null
+++ b/result/schemas/582906-1_0_0
@@ -0,0 +1 @@
+./test/schemas/582906-1_0.xml validates
diff --git a/result/schemas/582906-1_0_0.err b/result/schemas/582906-1_0_0.err
new file mode 100644
index 00000000..e69de29b
diff --git a/result/schemas/582906-2_0_0 b/result/schemas/582906-2_0_0
new file mode 100644
index 00000000..e69de29b
diff --git a/result/schemas/582906-2_0_0.err b/result/schemas/582906-2_0_0.err
new file mode 100644
index 00000000..c1f8204a
--- /dev/null
+++ b/result/schemas/582906-2_0_0.err
@@ -0,0 +1 @@
+test/schemas/582906-2-prog1.xsd:9: element include: Schemas parser error : Element '{http://www.w3.org/2001/XMLSchema}include': The target namespace 'http://example.com/xml/Prog3' of the included/redefined schema 'test/schemas/582906-2-common.xsd' differs from 'http://example.com/xml/Prog1' of the including/redefining schema.
diff --git a/test/schemas/582906-1-common.xsd b/test/schemas/582906-1-common.xsd
new file mode 100644
index 00000000..aa7cbdae
--- /dev/null
+++ b/test/schemas/582906-1-common.xsd
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified">
+</xs:schema>
diff --git a/test/schemas/582906-1-prog1.xsd b/test/schemas/582906-1-prog1.xsd
new file mode 100644
index 00000000..33dde568
--- /dev/null
+++ b/test/schemas/582906-1-prog1.xsd
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Prog1"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Prog1">
+
+    <xs:include schemaLocation="582906-1-common.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-1-prog2-include.xsd b/test/schemas/582906-1-prog2-include.xsd
new file mode 100644
index 00000000..8701cfce
--- /dev/null
+++ b/test/schemas/582906-1-prog2-include.xsd
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified" attributeFormDefault="unqualified"
+           xml:lang="en">
+
+    <xs:include schemaLocation="582906-1-common.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-1-prog2.xsd b/test/schemas/582906-1-prog2.xsd
new file mode 100644
index 00000000..4528fff2
--- /dev/null
+++ b/test/schemas/582906-1-prog2.xsd
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Prog2"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Prog2">
+
+    <xs:include schemaLocation="582906-1-common.xsd"/>
+
+    <xs:include schemaLocation="582906-1-prog2-include.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-1_0.xml b/test/schemas/582906-1_0.xml
new file mode 100644
index 00000000..311d85fa
--- /dev/null
+++ b/test/schemas/582906-1_0.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CollectedOutput xmlns="http://example.com/xml/Aggregator"
+             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+             xsi:schemaLocation="http://example.com/xml/Aggregator
+             582906-1.xsd">5.3</CollectedOutput>
diff --git a/test/schemas/582906-1_0.xsd b/test/schemas/582906-1_0.xsd
new file mode 100644
index 00000000..578f5a4b
--- /dev/null
+++ b/test/schemas/582906-1_0.xsd
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Aggregator"
+           xmlns:prog1="http://example.com/xml/Prog1"
+           xmlns:prog2="http://example.com/xml/Prog2"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Aggregator">
+
+    <xs:import schemaLocation="582906-1-prog1.xsd"
+               namespace="http://example.com/xml/Prog1" />
+
+    <xs:import schemaLocation="582906-1-prog2.xsd"
+               namespace="http://example.com/xml/Prog2"
+               />
+
+    <xs:element name="CollectedOutput" type="xs:float"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-2-common.xsd b/test/schemas/582906-2-common.xsd
new file mode 100644
index 00000000..c3b8c378
--- /dev/null
+++ b/test/schemas/582906-2-common.xsd
@@ -0,0 +1,7 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Prog3">
+</xs:schema>
diff --git a/test/schemas/582906-2-prog1.xsd b/test/schemas/582906-2-prog1.xsd
new file mode 100644
index 00000000..5cd2d41d
--- /dev/null
+++ b/test/schemas/582906-2-prog1.xsd
@@ -0,0 +1,11 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Prog1"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Prog1">
+
+    <xs:include schemaLocation="582906-2-common.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-2-prog2-include.xsd b/test/schemas/582906-2-prog2-include.xsd
new file mode 100644
index 00000000..4985aa3b
--- /dev/null
+++ b/test/schemas/582906-2-prog2-include.xsd
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified" attributeFormDefault="unqualified"
+           xml:lang="en">
+
+    <xs:include schemaLocation="582906-2-common.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-2-prog2.xsd b/test/schemas/582906-2-prog2.xsd
new file mode 100644
index 00000000..9446f211
--- /dev/null
+++ b/test/schemas/582906-2-prog2.xsd
@@ -0,0 +1,13 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Prog2"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Prog2">
+
+    <xs:include schemaLocation="582906-2-common.xsd"/>
+
+    <xs:include schemaLocation="582906-2-prog2-include.xsd"/>
+
+</xs:schema>
diff --git a/test/schemas/582906-2_0.xml b/test/schemas/582906-2_0.xml
new file mode 100644
index 00000000..e928957c
--- /dev/null
+++ b/test/schemas/582906-2_0.xml
@@ -0,0 +1,5 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<CollectedOutput xmlns="http://example.com/xml/Aggregator"
+             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+             xsi:schemaLocation="http://example.com/xml/Aggregator
+             582906-2-0.xsd">5.3</CollectedOutput>
diff --git a/test/schemas/582906-2_0.xsd b/test/schemas/582906-2_0.xsd
new file mode 100644
index 00000000..e62ebb8c
--- /dev/null
+++ b/test/schemas/582906-2_0.xsd
@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<!-- $Id$ -->
+<xs:schema xmlns="http://example.com/xml/Aggregator"
+           xmlns:prog1="http://example.com/xml/Prog1"
+           xmlns:prog2="http://example.com/xml/Prog2"
+           xmlns:xs="http://www.w3.org/2001/XMLSchema"
+           elementFormDefault="qualified"
+           attributeFormDefault="unqualified"
+           targetNamespace="http://example.com/xml/Aggregator">
+
+    <xs:import schemaLocation="582906-2-prog1.xsd"
+               namespace="http://example.com/xml/Prog1" />
+
+    <xs:import schemaLocation="582906-2-prog2.xsd"
+               namespace="http://example.com/xml/Prog2"
+               />
+
+    <xs:element name="CollectedOutput" type="xs:float"/>
+
+</xs:schema>
diff --git a/xmlschemas.c b/xmlschemas.c
index e6211202..70fe3eb1 100644
--- a/xmlschemas.c
+++ b/xmlschemas.c
@@ -11039,14 +11039,15 @@ xmlSchemaParseIncludeOrRedefine(xmlSchemaParserCtxtPtr pctxt,
 	    */
 	    isChameleon = 1;
 	    if (bucket->parsed &&
-		(bucket->targetNamespace != pctxt->targetNamespace)) {
-		/*
-		* This is a sanity check, I dunno yet if this can happen.
-		*/
-		PERROR_INT("xmlSchemaParseIncludeOrRedefine",
-		    "trying to use an already parsed schema for a "
-		    "different targetNamespace");
-		return(-1);
+		bucket->origTargetNamespace != NULL) {
+		xmlSchemaCustomErr(ACTXT_CAST pctxt,
+		    XML_SCHEMAP_SRC_INCLUDE,
+		    node, NULL,
+		    "The target namespace of the included/redefined schema "
+		    "'%s' has to be absent or the same as the "
+		    "including/redefining schema's target namespace",
+		    schemaLocation, NULL);
+		goto exit_error;
 	    }
 	    bucket->targetNamespace = pctxt->targetNamespace;
 	}