diff --git a/loader/module.c b/loader/module.c
index e291b0d4611..9f409522b5b 100644
--- a/loader/module.c
+++ b/loader/module.c
@@ -635,15 +635,14 @@ enum binary_type MODULE_GetBinaryType( HANDLE hfile )
          */
         if (!memcmp( magic, "PE\0\0", 4 ))
         {
-            IMAGE_NT_HEADERS nt;
+            IMAGE_FILE_HEADER FileHeader;
 
-            if (SetFilePointer( hfile, header.mz.e_lfanew, NULL, SEEK_SET ) != -1 &&
-                ReadFile( hfile, &nt, sizeof(nt), &len, NULL ) && len == sizeof(nt))
+            if (ReadFile( hfile, &FileHeader, sizeof(FileHeader), &len, NULL ) && len == sizeof(FileHeader))
             {
-                if (nt.FileHeader.Characteristics & IMAGE_FILE_DLL) return BINARY_PE_DLL;
+                if (FileHeader.Characteristics & IMAGE_FILE_DLL) return BINARY_PE_DLL;
                 return BINARY_PE_EXE;
             }
-            return BINARY_UNKNOWN;
+            return BINARY_DOS;
         }
 
         if (!memcmp( magic, "NE", 2 ))
@@ -666,7 +665,7 @@ enum binary_type MODULE_GetBinaryType( HANDLE hfile )
                 }
             }
             /* Couldn't read header, so abort. */
-            return BINARY_UNKNOWN;
+            return BINARY_DOS;
         }
 
         /* Unknown extended header, but this file is nonetheless DOS-executable. */
diff --git a/server/mapping.c b/server/mapping.c
index ef1d4ccea55..0c7e4d96fc5 100644
--- a/server/mapping.c
+++ b/server/mapping.c
@@ -211,8 +211,13 @@ static int get_image_params( struct mapping *mapping )
     if (read( fd, &dos, sizeof(dos) ) != sizeof(dos)) goto error;
     if (dos.e_magic != IMAGE_DOS_SIGNATURE) goto error;
     if (lseek( fd, dos.e_lfanew, SEEK_SET ) == -1) goto error;
-    if (read( fd, &nt, sizeof(nt) ) != sizeof(nt)) goto error;
+
+    if (read( fd, &nt.Signature, sizeof(nt.Signature) ) != sizeof(nt.Signature)) goto error;
     if (nt.Signature != IMAGE_NT_SIGNATURE) goto error;
+    if (read( fd, &nt.FileHeader, sizeof(nt.FileHeader) ) != sizeof(nt.FileHeader)) goto error;
+    /* zero out Optional header in the case it's not present or partial */
+    memset(&nt.OptionalHeader, 0, sizeof(nt.OptionalHeader));
+    if (read( fd, &nt.OptionalHeader, nt.FileHeader.SizeOfOptionalHeader) != nt.FileHeader.SizeOfOptionalHeader) goto error;
 
     /* load the section headers */